Productivity · Side quest build
How to Vibe Code Your Own Superhuman Alternative
Read the thread. Reply from the keyboard. Done. Superhuman charges $25–$33 per person per month — that’s $300–$396 a year per person — 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.
Official pricing. Starter $25 through Business $33 per member per month, billed annually, as listed. Checked October 19, 2026.
Who this replacement is for
This build targets one person who lives in one Gmail inbox and wants it faster. The goal: open threads, reply, archive, and do it from the keyboard without leaving the page. 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.
Same build, different logo: this v1 also replaces Hey and Spark Mail — they all solve the same core job.
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 Superhuman you actually use.
| Estimate | What you get |
|---|---|
| 3 days | thread list, read, reply, keyboard shortcuts |
| 2 weeks+ | snippets, labels, split inbox, undo send |
| 3 months+ | AI drafting, read receipts, native apps, team comments — the part you should probably skip |
What a minimal Superhuman alternative needs
- a thread list with unread state, date, and a one-line preview
- a reading pane that loads the full thread and a reply box
- keyboard shortcuts for next, previous, archive, compose, and send
- send and archive through the connected mail account
- a sent and archived view that matches what the provider stored
Data model
Mailbox, Thread, Message, Shortcut
Integrations
Gmail API OAuth
Capability context
Astro, Alpine, D1
The guardrail
Connect mail only through OAuth, store refresh tokens encrypted, and never send a message without an explicit user action.
Deliberate non-goals
Do not build AI drafting, read receipts, split inboxes, or native apps. Help Scout already covers a shared support inbox.
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 “Swiftbox”, a deliberately focused alternative to Superhuman. 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 person who lives in one Gmail inbox and wants it faster. Primary outcome: open threads, reply, archive, and do it from the keyboard without leaving the page. Product principle: optimize the exact workflow below instead of copying the full breadth of Superhuman. 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 connects Gmail, opens the newest unread thread, replies from the keyboard, and archives it. 2. The owner composes a new message, sends it, and finds that thread in sent mail after a refresh. 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. Thread list with unread state, date, preview, and keyboard focus. 2. Thread pane with messages, reply box, and archive and send actions. 3. Compose view with to, subject, body, and a send shortcut. CORE CAPABILITIES 1. a thread list with unread state, date, and a one-line preview 2. a reading pane that loads the full thread and a reply box 3. keyboard shortcuts for next, previous, archive, compose, and send 4. send and archive through the connected mail account 5. a sent and archived view that matches what the provider stored DETAILED BEHAVIOR AND BUSINESS RULES Treat these as server-enforced product requirements, not interface suggestions: 1. Exchange mail only through the OAuth-connected account and encrypt the refresh token at rest. 2. Send only after an explicit shortcut or button press, and keep provider thread ids as the source of truth. 3. Never store message bodies in logs, and isolate each mailbox to its owner. DATA MODEL AND LIFECYCLE Design a small relational schema centered on Mailbox, Thread, Message, Shortcut. 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 on Node.js. Add client JavaScript only for interactions that need browser state, browser APIs, drag-and-drop, or live updates. The core workflow must remain understandable if client JavaScript 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 Node.js and Astro. Use Astro for routing, layouts, and server-rendered pages. Start with ordinary HTML forms. Add client JavaScript only when the interface needs it. 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 Astro, Alpine, 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 Gmail API OAuth. 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 Connect mail only through OAuth, store refresh tokens encrypted, and never send a message without an explicit user action. 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. A send without a recipient is rejected and nothing reaches Gmail. 2. Archiving a thread removes it from the inbox list and leaves it readable in the archive view. 3. A revoked Google grant stops further send and list calls and asks the owner to reconnect. 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 AI drafting, read receipts, split inboxes, or native apps. Help Scout already covers a shared support inbox.
You are building a production-ready software product named “Swiftbox”, a deliberately focused alternative to Superhuman. 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 person who lives in one Gmail inbox and wants it faster. Primary outcome: open threads, reply, archive, and do it from the keyboard without leaving the page. Product principle: optimize the exact workflow below instead of copying the full breadth of Superhuman. 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 connects Gmail, opens the newest unread thread, replies from the keyboard, and archives it. 2. The owner composes a new message, sends it, and finds that thread in sent mail after a refresh. 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. Thread list with unread state, date, preview, and keyboard focus. 2. Thread pane with messages, reply box, and archive and send actions. 3. Compose view with to, subject, body, and a send shortcut. CORE CAPABILITIES 1. a thread list with unread state, date, and a one-line preview 2. a reading pane that loads the full thread and a reply box 3. keyboard shortcuts for next, previous, archive, compose, and send 4. send and archive through the connected mail account 5. a sent and archived view that matches what the provider stored DETAILED BEHAVIOR AND BUSINESS RULES Treat these as server-enforced product requirements, not interface suggestions: 1. Exchange mail only through the OAuth-connected account and encrypt the refresh token at rest. 2. Send only after an explicit shortcut or button press, and keep provider thread ids as the source of truth. 3. Never store message bodies in logs, and isolate each mailbox to its owner. DATA MODEL AND LIFECYCLE Design a small relational schema centered on Mailbox, Thread, Message, Shortcut. 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 TanStack Start and server-side React by default. Use server functions 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 Node.js and TanStack Start. Use TanStack Router for file-based routes, server functions for authenticated mutations, and server rendering for the first paint. Use a real SQL database with versioned migrations and an isolated test database. Access 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 Astro, Alpine, 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 Gmail API OAuth. 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 Connect mail only through OAuth, store refresh tokens encrypted, and never send a message without an explicit user action. 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. A send without a recipient is rejected and nothing reaches Gmail. 2. Archiving a thread removes it from the inbox list and leaves it readable in the archive view. 3. A revoked Google grant stops further send and list calls and asks the owner to reconnect. 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 AI drafting, read receipts, split inboxes, or native apps. Help Scout already covers a shared support inbox.
Frequently asked questions
How long does it take to build your own Superhuman?
A basic version — thread list, read, reply, keyboard shortcuts — takes about 3 days. Roughly 2 weeks+ gets you a solid v1 with snippets, labels, split inbox, undo send. Matching everything Superhuman really does (AI drafting, read receipts, native apps, team comments) is closer to 3 months+, which is exactly why you should scope down instead.
How much does Superhuman cost if I keep subscribing?
Superhuman runs $25–$33 per person per month on public paid plans, which is $300–$396 per year for every person on your team. A focused self-built replacement costs your build time plus close-to-zero hosting.
What stack should I use to build a Superhuman alternative?
The build prompt on this page ships in two flavors: Node.js plus Astro, and TanStack Start. The capability context for this product is Astro, Alpine, D1. I default to Astro because this site already runs that way. Use TanStack Start if React is what you write. The scope matters more than the framework.
What features does a minimal Superhuman replacement need?
A useful v1 needs: a thread list with unread state, date, and a one-line preview; a reading pane that loads the full thread and a reply box; keyboard shortcuts for next, previous, archive, compose, and send; send and archive through the connected mail account; a sent and archived view that matches what the provider stored. Everything else is scope creep until you personally miss it.
What should I deliberately not build?
Do not build AI drafting, read receipts, split inboxes, or native apps. Help Scout already covers a shared support inbox.
Does this build also replace Hey and Spark Mail?
Yes. Superhuman, Hey and Spark Mail all solve the same core job — open threads, reply, archive, and do it from the keyboard without leaving the page. The scoped v1 on this page covers what most people use any of them for, so one focused build replaces whichever you currently pay for.