Personal · Side quest build
Build your own Obsidian Sync
Your vault, your server, your problem now. Obsidian Sync charges $5–$10 per month — that’s $60–$120 a year — for something you can replace with focused software of your own. Here is the honest scope, the honest timeline, and the exact prompt to hand your coding agent.
Who this replacement is for
This build targets one Obsidian user syncing a private vault between a laptop, desktop, and phone. The goal: keep every device’s vault current through your own server without the server ever reading a note. If you need more than that, keep paying — the point of building it yourself is owning a tool shaped exactly like your workflow, not re-implementing a venture-funded roadmap.
How long it actually takes
One number would be a lie, so here are three. Each tier is a real, usable product — pick the one that matches how much of Obsidian Sync you actually use.
| Estimate | What you get |
|---|---|
| 2 days | versioned file storage, restore, basic sync |
| 1 week | end-to-end encryption, conflict copies, selective sync |
| 1 month+ | automatic merge, vault sharing, mobile edge cases — the part you should probably skip |
What a minimal Obsidian Sync alternative needs
- versioned file storage with per-file history and restore
- client-side end-to-end encryption before anything leaves the device
- conflict copies when two devices edit the same note offline
- selective sync for chosen folders per device
- a sync status view with pending, synced, and conflicted files
Data model
Vault, Device, FileVersion, SyncOperation, ConflictCopy
Integrations
Obsidian plugin API, WebCrypto
Capability context
Workers, R2, D1
The guardrail
Encrypt content and filenames on the client with a key the server never sees; losing the passphrase loses the vault, and say so.
Deliberate non-goals
Do not build real-time collaborative editing, vault sharing, a web note editor, or automatic merging of conflicting edits.
The complete build prompt
Copy this into your coding agent of choice. It is scoped for a useful v1 — journeys, screens, business rules, data model, security, tests, and acceptance scenarios included. Pick your stack:
You are building a production-ready software product named “Syncnest”, a deliberately focused alternative to Obsidian Sync. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components. WORKING AGREEMENT Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests. PRODUCT BRIEF Primary user: one Obsidian user syncing a private vault between a laptop, desktop, and phone. Primary outcome: keep every device’s vault current through your own server without the server ever reading a note. Product principle: optimize the exact workflow below instead of copying the full breadth of Obsidian Sync. A first-time user should understand what to do from the interface itself, without a tour or documentation. END-TO-END USER JOURNEYS Implement all of these flows through the real interface and persistent data layer: 1. The owner deploys the server, creates a vault with a passphrase-derived key, connects the first device, and watches the initial encrypted upload complete. 2. The owner edits the same note on two offline devices; on reconnect one version wins, the other becomes a clearly named conflict copy, and nothing is lost. 3. The owner enables selective sync on the phone to skip an attachments folder, then restores yesterday’s version of a note from file history on the desktop. SCREENS AND INFORMATION ARCHITECTURE Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state. 1. Setup: server address, vault creation, passphrase entry with a blunt no-recovery warning, and device pairing with a verification code. 2. Sync status: per-file pending, uploading, synced, and conflicted states, last sync time, transfer progress, and a pause control. 3. File history: versions per file with device and timestamp, size deltas, restore-as-copy action, and retention settings. 4. Selective sync: folder tree with per-device include and exclude toggles, projected storage use, and an apply confirmation. CORE CAPABILITIES 1. versioned file storage with per-file history and restore 2. client-side end-to-end encryption before anything leaves the device 3. conflict copies when two devices edit the same note offline 4. selective sync for chosen folders per device 5. a sync status view with pending, synced, and conflicted files DETAILED BEHAVIOR AND BUSINESS RULES Treat these as server-enforced product requirements, not interface suggestions: 1. Encrypt file contents and paths on the client; the server stores only ciphertext, sizes, and opaque version metadata. 2. Never overwrite a newer remote version blindly: writes are conditional on the expected parent version, and a mismatch produces a conflict copy. 3. Every upload creates an immutable new version; deletes are tombstones so history and restore survive across devices. 4. Authenticate each device with its own revocable credential so a lost device can be cut off without rotating the vault key. DATA MODEL AND LIFECYCLE Design a small relational schema centered on Vault, Device, FileVersion, SyncOperation, ConflictCopy. Before implementing it, document: 1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes. 2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes. 3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable. 4. Archive, retention, and deletion behavior, including what happens to dependent records and external files. 5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable. Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant. USERS, AUTHENTICATION, AND PERMISSIONS Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested. INTERACTION AND VISUAL DIRECTION The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails. Start with server-rendered Astro pages and ordinary HTML forms. Use HTMX for form submissions, partial navigation, and server-driven updates, then Alpine.js only for small local browser state. The core workflow must remain understandable if either enhancement layer fails. Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent. TECHNICAL DIRECTION Build this version with the AHA stack: Astro for routing, layouts, and server-rendered pages; HTMX for interactions that benefit from HTML fragment responses; and Alpine.js for small, local interface state. Prefer Cloudflare D1 for relational persistence, R2 for object storage, Workers for server endpoints and scheduled work, Durable Objects only for coordinated real-time state, and Workflows or Queues for durable background jobs—but only when the product requirements call for them. Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly. The product brief currently identifies Workers, R2, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface. Integrate with Obsidian plugin API and WebCrypto. For every integration: - List required environment variables in an .env.example without real secrets. - Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path. - Verify inbound signatures and deduplicate provider events where supported. - Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs. - Define retry, backoff, and idempotency behavior for any side effect that can be repeated. SECURITY AND PRIVACY Encrypt content and filenames on the client with a key the server never sees; losing the passphrase loses the vault, and say so. Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections. ACCEPTANCE SCENARIOS Automate these app-specific scenarios at the most appropriate level: 1. Given the same note edited on two offline devices, syncing yields the latest version plus a conflict copy named with device and time, never a silent overwrite. 2. Given a stolen server backup, an attacker holds only ciphertext and opaque paths and cannot decrypt a single note without the passphrase. 3. Given a folder excluded on the phone, its files stop downloading there but keep syncing between the other devices, and re-including restores them. TESTING Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command. OPERATIONS AND FAILURE RECOVERY Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack. DELIVERABLES Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product. DEFINITION OF DONE The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder. NON-GOALS Do not build real-time collaborative editing, vault sharing, a web note editor, or automatic merging of conflicting edits.
You are building a production-ready software product named “Syncnest”, a deliberately focused alternative to Obsidian Sync. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components. WORKING AGREEMENT Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests. PRODUCT BRIEF Primary user: one Obsidian user syncing a private vault between a laptop, desktop, and phone. Primary outcome: keep every device’s vault current through your own server without the server ever reading a note. Product principle: optimize the exact workflow below instead of copying the full breadth of Obsidian Sync. A first-time user should understand what to do from the interface itself, without a tour or documentation. END-TO-END USER JOURNEYS Implement all of these flows through the real interface and persistent data layer: 1. The owner deploys the server, creates a vault with a passphrase-derived key, connects the first device, and watches the initial encrypted upload complete. 2. The owner edits the same note on two offline devices; on reconnect one version wins, the other becomes a clearly named conflict copy, and nothing is lost. 3. The owner enables selective sync on the phone to skip an attachments folder, then restores yesterday’s version of a note from file history on the desktop. SCREENS AND INFORMATION ARCHITECTURE Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state. 1. Setup: server address, vault creation, passphrase entry with a blunt no-recovery warning, and device pairing with a verification code. 2. Sync status: per-file pending, uploading, synced, and conflicted states, last sync time, transfer progress, and a pause control. 3. File history: versions per file with device and timestamp, size deltas, restore-as-copy action, and retention settings. 4. Selective sync: folder tree with per-device include and exclude toggles, projected storage use, and an apply confirmation. CORE CAPABILITIES 1. versioned file storage with per-file history and restore 2. client-side end-to-end encryption before anything leaves the device 3. conflict copies when two devices edit the same note offline 4. selective sync for chosen folders per device 5. a sync status view with pending, synced, and conflicted files DETAILED BEHAVIOR AND BUSINESS RULES Treat these as server-enforced product requirements, not interface suggestions: 1. Encrypt file contents and paths on the client; the server stores only ciphertext, sizes, and opaque version metadata. 2. Never overwrite a newer remote version blindly: writes are conditional on the expected parent version, and a mismatch produces a conflict copy. 3. Every upload creates an immutable new version; deletes are tombstones so history and restore survive across devices. 4. Authenticate each device with its own revocable credential so a lost device can be cut off without rotating the vault key. DATA MODEL AND LIFECYCLE Design a small relational schema centered on Vault, Device, FileVersion, SyncOperation, ConflictCopy. Before implementing it, document: 1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes. 2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes. 3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable. 4. Archive, retention, and deletion behavior, including what happens to dependent records and external files. 5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable. Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant. USERS, AUTHENTICATION, AND PERMISSIONS Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested. INTERACTION AND VISUAL DIRECTION The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails. Render with React Server Components by default. Use Server Actions for authenticated form mutations and add Client Components only for interactions that genuinely require browser state, browser APIs, drag-and-drop, or live updates. The core workflow must remain understandable before client-side JavaScript finishes loading. Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent. TECHNICAL DIRECTION Build this version with Next.js, the App Router, and TypeScript. Use Server Components by default, Server Actions for authenticated mutations, and Route Handlers for public APIs, OAuth callbacks, webhooks, feeds, uploads, and downloads. Use PostgreSQL through Drizzle ORM with versioned migrations and an isolated test database. Access S3-compatible object storage through a server-only adapter, and run slow or retryable work in a real job or workflow system instead of the request lifecycle. Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly. The product brief currently identifies Workers, R2, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface. Integrate with Obsidian plugin API and WebCrypto. For every integration: - List required environment variables in an .env.example without real secrets. - Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path. - Verify inbound signatures and deduplicate provider events where supported. - Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs. - Define retry, backoff, and idempotency behavior for any side effect that can be repeated. SECURITY AND PRIVACY Encrypt content and filenames on the client with a key the server never sees; losing the passphrase loses the vault, and say so. Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections. ACCEPTANCE SCENARIOS Automate these app-specific scenarios at the most appropriate level: 1. Given the same note edited on two offline devices, syncing yields the latest version plus a conflict copy named with device and time, never a silent overwrite. 2. Given a stolen server backup, an attacker holds only ciphertext and opaque paths and cannot decrypt a single note without the passphrase. 3. Given a folder excluded on the phone, its files stop downloading there but keep syncing between the other devices, and re-including restores them. TESTING Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command. OPERATIONS AND FAILURE RECOVERY Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack. DELIVERABLES Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product. DEFINITION OF DONE The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder. NON-GOALS Do not build real-time collaborative editing, vault sharing, a web note editor, or automatic merging of conflicting edits.
You are building a production-ready software product named “Syncnest”, a deliberately focused alternative to Obsidian Sync. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components. WORKING AGREEMENT Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests. PRODUCT BRIEF Primary user: one Obsidian user syncing a private vault between a laptop, desktop, and phone. Primary outcome: keep every device’s vault current through your own server without the server ever reading a note. Product principle: optimize the exact workflow below instead of copying the full breadth of Obsidian Sync. A first-time user should understand what to do from the interface itself, without a tour or documentation. END-TO-END USER JOURNEYS Implement all of these flows through the real interface and persistent data layer: 1. The owner deploys the server, creates a vault with a passphrase-derived key, connects the first device, and watches the initial encrypted upload complete. 2. The owner edits the same note on two offline devices; on reconnect one version wins, the other becomes a clearly named conflict copy, and nothing is lost. 3. The owner enables selective sync on the phone to skip an attachments folder, then restores yesterday’s version of a note from file history on the desktop. SCREENS AND INFORMATION ARCHITECTURE Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state. 1. Setup: server address, vault creation, passphrase entry with a blunt no-recovery warning, and device pairing with a verification code. 2. Sync status: per-file pending, uploading, synced, and conflicted states, last sync time, transfer progress, and a pause control. 3. File history: versions per file with device and timestamp, size deltas, restore-as-copy action, and retention settings. 4. Selective sync: folder tree with per-device include and exclude toggles, projected storage use, and an apply confirmation. CORE CAPABILITIES 1. versioned file storage with per-file history and restore 2. client-side end-to-end encryption before anything leaves the device 3. conflict copies when two devices edit the same note offline 4. selective sync for chosen folders per device 5. a sync status view with pending, synced, and conflicted files DETAILED BEHAVIOR AND BUSINESS RULES Treat these as server-enforced product requirements, not interface suggestions: 1. Encrypt file contents and paths on the client; the server stores only ciphertext, sizes, and opaque version metadata. 2. Never overwrite a newer remote version blindly: writes are conditional on the expected parent version, and a mismatch produces a conflict copy. 3. Every upload creates an immutable new version; deletes are tombstones so history and restore survive across devices. 4. Authenticate each device with its own revocable credential so a lost device can be cut off without rotating the vault key. DATA MODEL AND LIFECYCLE Design a small relational schema centered on Vault, Device, FileVersion, SyncOperation, ConflictCopy. Before implementing it, document: 1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes. 2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes. 3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable. 4. Archive, retention, and deletion behavior, including what happens to dependent records and external files. 5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable. Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant. USERS, AUTHENTICATION, AND PERMISSIONS Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested. INTERACTION AND VISUAL DIRECTION The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails. Start with server-rendered Blade views and ordinary forms. Use Livewire for focused server-driven interactions and Alpine.js only for small local interface state. The core workflow must remain understandable without relying on a client-side application shell. Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent. TECHNICAL DIRECTION Build this version with Laravel, PHP, Blade, Livewire, and Alpine.js. Use controllers and Blade forms for durable navigation, Livewire for focused interactions, Form Requests for validation, Policies and Gates for authorization, and small application actions or services for domain transitions. Use Eloquent with migrations, database constraints, and transactions; Laravel Storage for private S3-compatible files; queued Jobs for retryable work; the Scheduler for recurring work; and Notifications or Mail for email. Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly. The product brief currently identifies Workers, R2, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface. Integrate with Obsidian plugin API and WebCrypto. For every integration: - List required environment variables in an .env.example without real secrets. - Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path. - Verify inbound signatures and deduplicate provider events where supported. - Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs. - Define retry, backoff, and idempotency behavior for any side effect that can be repeated. SECURITY AND PRIVACY Encrypt content and filenames on the client with a key the server never sees; losing the passphrase loses the vault, and say so. Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections. ACCEPTANCE SCENARIOS Automate these app-specific scenarios at the most appropriate level: 1. Given the same note edited on two offline devices, syncing yields the latest version plus a conflict copy named with device and time, never a silent overwrite. 2. Given a stolen server backup, an attacker holds only ciphertext and opaque paths and cannot decrypt a single note without the passphrase. 3. Given a folder excluded on the phone, its files stop downloading there but keep syncing between the other devices, and re-including restores them. TESTING Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command. OPERATIONS AND FAILURE RECOVERY Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack. DELIVERABLES Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product. DEFINITION OF DONE The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder. NON-GOALS Do not build real-time collaborative editing, vault sharing, a web note editor, or automatic merging of conflicting edits.
You are building a production-ready software product named “Syncnest”, a deliberately focused alternative to Obsidian Sync. Build a complete, usable vertical slice—not a landing page, static mockup, or disconnected collection of components. WORKING AGREEMENT Before writing implementation code, produce a short technical plan that names the routes or pages, server actions or endpoints, data tables, important state transitions, authorization boundaries, background jobs, and external adapters. Resolve contradictions in favor of the narrow audience and non-goals below. Prefer a small, legible architecture over speculative abstraction, but do not omit persistence, validation, error handling, or tests. PRODUCT BRIEF Primary user: one Obsidian user syncing a private vault between a laptop, desktop, and phone. Primary outcome: keep every device’s vault current through your own server without the server ever reading a note. Product principle: optimize the exact workflow below instead of copying the full breadth of Obsidian Sync. A first-time user should understand what to do from the interface itself, without a tour or documentation. END-TO-END USER JOURNEYS Implement all of these flows through the real interface and persistent data layer: 1. The owner deploys the server, creates a vault with a passphrase-derived key, connects the first device, and watches the initial encrypted upload complete. 2. The owner edits the same note on two offline devices; on reconnect one version wins, the other becomes a clearly named conflict copy, and nothing is lost. 3. The owner enables selective sync on the phone to skip an attachments folder, then restores yesterday’s version of a note from file history on the desktop. SCREENS AND INFORMATION ARCHITECTURE Build these as coherent responsive views. Each screen must specify its primary action, secondary actions, visible status, validation feedback, empty state, loading or pending state, success confirmation, and recoverable failure state. 1. Setup: server address, vault creation, passphrase entry with a blunt no-recovery warning, and device pairing with a verification code. 2. Sync status: per-file pending, uploading, synced, and conflicted states, last sync time, transfer progress, and a pause control. 3. File history: versions per file with device and timestamp, size deltas, restore-as-copy action, and retention settings. 4. Selective sync: folder tree with per-device include and exclude toggles, projected storage use, and an apply confirmation. CORE CAPABILITIES 1. versioned file storage with per-file history and restore 2. client-side end-to-end encryption before anything leaves the device 3. conflict copies when two devices edit the same note offline 4. selective sync for chosen folders per device 5. a sync status view with pending, synced, and conflicted files DETAILED BEHAVIOR AND BUSINESS RULES Treat these as server-enforced product requirements, not interface suggestions: 1. Encrypt file contents and paths on the client; the server stores only ciphertext, sizes, and opaque version metadata. 2. Never overwrite a newer remote version blindly: writes are conditional on the expected parent version, and a mismatch produces a conflict copy. 3. Every upload creates an immutable new version; deletes are tombstones so history and restore survive across devices. 4. Authenticate each device with its own revocable credential so a lost device can be cut off without rotating the vault key. DATA MODEL AND LIFECYCLE Design a small relational schema centered on Vault, Device, FileVersion, SyncOperation, ConflictCopy. Before implementing it, document: 1. Each table’s purpose, primary key, ownership or tenant boundary, timestamps, status fields, and important attributes. 2. Foreign keys, uniqueness constraints, check constraints, indexes needed by the named screens, and transaction boundaries for multi-record changes. 3. The allowed lifecycle or state transitions, who may trigger each transition, which transitions are terminal or reversible, and what audit history must remain immutable. 4. Archive, retention, and deletion behavior, including what happens to dependent records and external files. 5. Idempotency strategy for submissions, jobs, imports, notifications, webhooks, or retries where applicable. Use migrations rather than ad-hoc schema creation. Store time instants consistently and retain named timezone context whenever local schedules or dates matter. Never rely on a counter, disabled button, or client-side check to preserve a business invariant. USERS, AUTHENTICATION, AND PERMISSIONS Implement only the roles required by the stated audience. Make the ownership and visibility model explicit before coding. Enforce authorization in every server-side query and mutation, including search, exports, attachments, live updates, and guessed URLs—not merely by hiding controls. Use secure session defaults, protect state-changing requests, and provide an understandable signed-out, expired-session, and forbidden state. Seed distinct users when multiple roles are required so permissions can be demonstrated and tested. INTERACTION AND VISUAL DIRECTION The product should feel fast, calm, focused, and credible rather than like a generic admin template. Use a clear visual hierarchy, restrained color, readable typography, generous hit targets, and consistent placement for primary actions. Start with server-rendered HTML and progressively enhance only the interactions that benefit from it. The core workflow must remain understandable if enhancement fails. Start with server-rendered Rails views and ordinary forms. Use Turbo for navigation, submissions, and server-driven updates, then Stimulus only for small browser-side behavior. Do not turn the product into a client-side SPA, and keep the core workflow usable when enhancement fails. Design mobile layouts intentionally instead of simply stacking desktop panels. Support keyboard navigation, visible focus, semantic landmarks, explicit labels, useful page titles, reduced-motion preferences, and screen-reader announcements for asynchronous results. Never use color alone to communicate state. Destructive actions require clear scope and confirmation; safe repeated actions should be idempotent. TECHNICAL DIRECTION Build this version with Ruby on Rails and Hotwire: Turbo for navigation, form submissions, and server-driven updates, and Stimulus for small browser-side behavior. Use RESTful controllers with strong parameters and explicit authorization, with domain transitions in testable models or small application services. Use Active Record migrations plus database-level constraints and transactions; Active Storage with an S3-compatible service for private files; Active Job with a durable queue backend for retryable work; Action Mailer for email; and Action Cable only when live updates are required. Keep domain rules in testable server-side modules instead of route handlers or UI components. Separate persistence, external providers, and background work behind small interfaces without building a framework. Prefer ordinary HTML forms and URLs for durable navigation; use optimistic interaction only when failure can be reconciled clearly. The product brief currently identifies Workers, R2, D1 as capability context. Preserve any required native, browser-only, edge, storage, real-time, or background-processing capability through a narrow adapter appropriate to the selected framework. If the core workflow genuinely requires native or browser APIs, keep that runtime as the primary execution surface rather than simulating inaccessible capabilities or inventing an unnecessary web surface. Integrate with Obsidian plugin API and WebCrypto. For every integration: - List required environment variables in an .env.example without real secrets. - Add a small adapter with timeouts, normalized errors, and a deterministic local fake or development path. - Verify inbound signatures and deduplicate provider events where supported. - Keep credentials server-side, encrypt long-lived provider tokens at rest, and redact secrets and sensitive payloads from logs. - Define retry, backoff, and idempotency behavior for any side effect that can be repeated. SECURITY AND PRIVACY Encrypt content and filenames on the client with a key the server never sees; losing the passphrase loses the vault, and say so. Validate, normalize, and length-limit all untrusted input on the server. Escape rendered content by default, sanitize any intentionally accepted markup, rate-limit public or abuse-prone actions, and use private object storage plus short-lived authorized URLs for sensitive files. Collect the minimum personal data necessary for the named workflow. Document retention and deletion behavior. Add specific protections for the riskier surfaces in this app, such as uploads, redirects, outbound requests, email delivery, OAuth, webhooks, CSV import or export, and real-time connections. ACCEPTANCE SCENARIOS Automate these app-specific scenarios at the most appropriate level: 1. Given the same note edited on two offline devices, syncing yields the latest version plus a conflict copy named with device and time, never a silent overwrite. 2. Given a stolen server backup, an attacker holds only ciphertext and opaque paths and cannot decrypt a single note without the passphrase. 3. Given a folder excluded on the phone, its files stop downloading there but keep syncing between the other devices, and re-including restores them. TESTING Add focused unit tests for state transitions, authorization predicates, normalization, date or money calculations, and other risky domain rules. Add integration tests for persistence constraints and each external adapter’s success, timeout, retry, and rejection paths. Add at least one browser-level test for every end-to-end journey above, including one small-screen viewport. Tests must use isolated data and run through a documented single command. OPERATIONS AND FAILURE RECOVERY Add structured server logs with request, job, or event correlation IDs but no secrets or unnecessarily sensitive data. Make failures actionable in both the interface and logs. Background work must expose pending, succeeded, failed, and retrying states where relevant; do not silently swallow errors. Include safe database migration and rollback guidance, seed data, backup and restore notes, external-data cleanup behavior, and a basic health or diagnostic path appropriate to the stack. DELIVERABLES Ship the working application, migrations, representative seed data, tests, .env.example, and a concise README. The README must cover prerequisites, local setup, environment variables, migrations, seed and test commands, deployment, integration setup, backup and restore, security decisions, and known limitations. Seed data should exercise the happy path plus at least one empty, failed, overdue, expired, archived, or permission-restricted state relevant to the product. DEFINITION OF DONE The app is complete when a fresh developer can follow the README, create and migrate the database, run the app, sign in as each relevant role, complete every named journey using real persisted data, refresh without losing state, recover from common failures, and use the core interface on phone and desktop. All acceptance scenarios pass, permission boundaries are covered by tests, and no core screen is left as a placeholder. NON-GOALS Do not build real-time collaborative editing, vault sharing, a web note editor, or automatic merging of conflicting edits.
Build just one piece
Not ready to replace all of Obsidian Sync? Fine. These are the peculiar sub-problems hiding inside it — the parts that are actually interesting to build. Each one is a standalone prompt, scoped to an evening, no strings attached to the full build.
The conditional write that turns conflicts into copiesTwo offline edits, one winner, zero silent overwrites.
Build conflict handling for a file sync server, built on a single primitive: the compare-and-swap upload. Every stored file version has an ID, and every upload declares the parent version it was based on. The server accepts the write only when the declared parent is still the latest; otherwise it rejects with the current head, atomically, so two devices racing produce exactly one winner even on simultaneous uploads. The losing device then resolves locally: it keeps the remote winner as the file's current content and preserves its own rejected edit as a conflict copy, a sibling file named with the device and timestamp, so nothing anyone typed is ever lost. Never merge automatically; a wrong merge in a notes vault is worse than a visible conflict. Handle repeated offline edits building on the losing chain, each rejection produces one conflict copy, not a cascade, and surface conflicted files prominently in the sync status view until the owner deals with them. Done when: simultaneous uploads from two devices yield one winner and one correctly named conflict copy, no sequence of offline edits can silently discard content, and the race is decided atomically on the server.
Encrypting the filenames tooA stolen server backup should read as pure noise, paths included.
Build the client-side encryption layer for a note sync system where the server must never learn anything, including what your files are called. Derive a vault key from the passphrase with a memory-hard KDF and a stored salt; the key and passphrase never leave the device. Encrypt every file's content with an authenticated cipher and a fresh random nonce per version. Then the part everyone skips: encrypt the paths too, since filenames like "resignation-letter.md" are content. Encrypt each path component deterministically under a dedicated key, so equal names map to equal ciphertexts and the server can still address folders as opaque tokens, while accepting that this leaks folder structure and name-equality but not names. The server ends up storing ciphertext blobs, sizes, and opaque identifiers, nothing else. Be blunt in the UI: losing the passphrase loses the vault, there is no recovery, and build a key-check value so a mistyped passphrase fails fast instead of decrypting garbage. Done when: a full dump of server storage reveals no plaintext content or filename anywhere, a wrong passphrase is rejected immediately at unlock, and every version decrypts only with authentication intact.
Deletes that leave tombstonesIn a sync system, deletion is just another version.
Build version history and deletion for a multi-device file sync system, where every change is an immutable new version and nothing is ever destroyed in place. Each upload appends a version with device, timestamp, size, and a pointer to its content; the file's current state is simply its latest version. Deletion follows the same rule: it appends a tombstone version rather than removing anything, which is what makes deletes propagate correctly, another device syncing later sees the tombstone and removes its local copy, instead of seeing an absence and helpfully re-uploading the file, resurrecting it forever. Restore is non-destructive: restoring yesterday's version appends it as a new head (or as a copy alongside), so the history never rewrites. Add retention so storage stays sane, keep all versions for a window, then thin to daily, but never prune a tombstone while any paired device hasn't seen it, or the resurrection bug returns through the back door. Done when: deleting on one device removes the file on another after sync with no re-upload loop, a file's full history survives its deletion, and restore-as-copy never mutates existing versions.
Selective sync without wrecking the other devicesThe phone skips the attachments folder. The laptops never notice.
Build per-device selective sync for a vault syncing system: the owner excludes folders on a device, and only that device's behavior changes. Exclusions are per-device state, not vault state: the phone excluding an attachments folder stops downloading it there, while every other device keeps syncing it fully. The excluded device must still know the folder exists, keep skeleton metadata, or it will misread the folder's absence as a deletion and propagate a purge to everyone, which is the classic catastrophic bug in this feature. Uploads from other devices into an excluded folder simply never download to the excluding device. Re-including restores the folder by downloading current heads, not by replaying every historical version. Handle the boundary cases: a file moved from an excluded folder into an included one starts syncing; an exclusion applied while downloads are in flight cancels them cleanly; and show projected storage impact before applying, since freeing space is the entire point. Done when: excluding a folder on one device provably sends no deletions to any other device, re-including restores current content, and a move across the exclusion boundary syncs correctly.
Frequently asked questions
How long does it take to build your own Obsidian Sync?
A basic version — versioned file storage, restore, basic sync — takes about 2 days. Roughly 1 week gets you a solid v1 with end-to-end encryption, conflict copies, selective sync. Matching everything Obsidian Sync really does (automatic merge, vault sharing, mobile edge cases) is closer to 1 month+, which is exactly why you should scope down instead.
How much does Obsidian Sync cost if I keep subscribing?
Obsidian Sync runs $5–$10 per month on public paid plans, which is $60–$120 per year. A focused self-built replacement costs your build time plus close-to-zero hosting.
What stack should I use to build a Obsidian Sync alternative?
The build prompt on this page ships in four flavors: the AHA stack (Astro, HTMX, Alpine.js), Next.js, Laravel, and Ruby on Rails. The capability context for this product is Workers, R2, D1. Pick the stack you already know — the scope matters more than the framework.
What features does a minimal Obsidian Sync replacement need?
A useful v1 needs: versioned file storage with per-file history and restore; client-side end-to-end encryption before anything leaves the device; conflict copies when two devices edit the same note offline; selective sync for chosen folders per device; a sync status view with pending, synced, and conflicted files. Everything else is scope creep until you personally miss it.
What should I deliberately not build?
Do not build real-time collaborative editing, vault sharing, a web note editor, or automatic merging of conflicting edits.