Operations · Side quest build

Build your own Sentry

Your bugs deserve better than a log file. Sentry charges $26–$89 per month — that’s $312–$1068 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.

from 3 daysOwn your error data

Who this replacement is for

This build targets a developer running a few production apps who wants error reports on infrastructure they control. The goal: capture errors from your own apps, group the noise into issues, and hear about new ones fast. 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 Sentry you actually use.

EstimateWhat you get
3 daysingest endpoint, fingerprint grouping, issue list, alerts
2 weeks+releases, regression reopening, thresholds, secret scrubbing
3 months+source maps, sdk zoo, tracing, session replay — the part you should probably skip

What a minimal Sentry alternative needs

Data model

Project, Event, Issue, Release, AlertRule

Integrations

transactional email

Capability context

Astro, Workers, D1

The guardrail

Authenticate ingest with per-project keys, scrub obvious secrets and personal data on arrival, and cap event size and rate per project.

Deliberate non-goals

Do not build APM, distributed tracing, session replay, or SDKs for languages you do not use.

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 “Crashpad”, a deliberately focused alternative to Sentry. 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: a developer running a few production apps who wants error reports on infrastructure they control.
Primary outcome: capture errors from your own apps, group the noise into issues, and hear about new ones fast.
Product principle: optimize the exact workflow below instead of copying the full breadth of Sentry. 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 creates a project, drops the tiny SDK snippet into an app, triggers a test error, and sees it arrive as a new unresolved issue with a readable stack trace.
2. A deploy ships a regression; hundreds of identical events group into one issue tagged with the new release, and the owner receives exactly one alert.
3. The owner resolves an issue and ships a fix; when the error returns in a later release, the issue reopens as a regression and alerts again.

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. Issues list: unresolved, resolved, and ignored tabs, event counts, first and last seen, affected release range, and bulk state actions.
2. Issue detail: grouped stack trace, event-count sparkline, sample events with context, release tags, and resolve or ignore actions.
3. Project settings: ingest key with rotate action, rate and payload limits, scrubbing-pattern preview, and alert thresholds.
4. Alerts: per-project rule list, new-issue and regression triggers, recipients, recent deliveries, and mute state.

CORE CAPABILITIES
1. a tiny SDK and ingest endpoint accepting errors with stack trace, context, and release
2. fingerprint grouping so a thousand identical events become one issue
3. unresolved, resolved, and ignored issue states with regression reopening
4. release tagging with first-seen and last-seen versions per issue
5. email alerts for new issues and regressions with per-project thresholds

DETAILED BEHAVIOR AND BUSINESS RULES
Treat these as server-enforced product requirements, not interface suggestions:
1. Authenticate every ingest request with a per-project key, enforce per-project rate and payload limits, and drop rather than queue traffic over the cap.
2. Compute fingerprints server-side from exception type and normalized stack frames so a misbehaving client cannot split or merge issues.
3. Scrub configured secret and personal-data patterns before storage and never persist the raw unscrubbed payload.
4. Reopen a resolved issue as a regression only when an event arrives from a release newer than the resolving one; older releases never reopen it.

DATA MODEL AND LIFECYCLE
Design a small relational schema centered on Project, Event, Issue, Release, AlertRule. 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 Astro, Workers, 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 transactional email. 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
Authenticate ingest with per-project keys, scrub obvious secrets and personal data on arrival, and cap event size and rate per project.
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 five hundred identical errors in a minute, the project stores them under one issue, respects the rate cap, and sends a single new-issue alert.
2. Given an event carrying an unknown or invalid ingest key, it is rejected without revealing whether the project exists.
3. Given an issue marked ignored, further matching events increment its counts silently and trigger no alerts until the state changes.

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 APM, distributed tracing, session replay, or SDKs for languages you do not use.

Frequently asked questions

How long does it take to build your own Sentry?

A basic version — ingest endpoint, fingerprint grouping, issue list, alerts — takes about 3 days. Roughly 2 weeks+ gets you a solid v1 with releases, regression reopening, thresholds, secret scrubbing. Matching everything Sentry really does (source maps, sdk zoo, tracing, session replay) is closer to 3 months+, which is exactly why you should scope down instead.

How much does Sentry cost if I keep subscribing?

Sentry runs $26–$89 per month on public paid plans, which is $312–$1068 per year. A focused self-built replacement costs your build time plus close-to-zero hosting.

What stack should I use to build a Sentry 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 Astro, Workers, D1. Pick the stack you already know — the scope matters more than the framework.

What features does a minimal Sentry replacement need?

A useful v1 needs: a tiny SDK and ingest endpoint accepting errors with stack trace, context, and release; fingerprint grouping so a thousand identical events become one issue; unresolved, resolved, and ignored issue states with regression reopening; release tagging with first-seen and last-seen versions per issue; email alerts for new issues and regressions with per-project thresholds. Everything else is scope creep until you personally miss it.

What should I deliberately not build?

Do not build APM, distributed tracing, session replay, or SDKs for languages you do not use.

Prompt copied. Go ship it.