Sentry
Infra / DevOps · Freemium
Overview
An error monitoring tool for software. When an app crashes or throws an error, Sentry captures it with the details a developer needs to fix it: the stack trace, the exact line of code, the release, the environment, and the events leading up to the crash. It groups repeats of the same error together so one problem does not flood the view. David Cramer first published it as an open source project in 2008, and the company behind the hosted service, legally named Functional Software, was founded in 2012 by Cramer and Chris Jennings in San Francisco. The code is still public under a source available license, and Sentry can be self hosted, though most users are on the hosted service.
What people use it for
Developers use Sentry to find out about errors in production before users report them, and to get enough detail to reproduce and fix each one. Teams triage the incoming stream of issues, deciding what to fix now and what to ignore. They tie errors to a specific release so they can see which deploy introduced a problem and roll back if needed. They watch session replays to see what a user did in the seconds before a crash. They use performance tracing to find slow endpoints and slow database calls. Mobile teams track crashes across app versions and devices. Backend teams route errors from many services into one place with alerting into Slack or email so the right team hears about a break quickly.
Key capabilities
Sentry captures unhandled errors, groups duplicates into issues, and shows the stack trace, the exact line, the release, the environment, and the events leading up to the crash. Beyond errors it offers performance tracing across services, session replay that plays back what the user did before an error on web and mobile, profiling that points to the slow function, cron and uptime monitoring, structured logs, and custom metrics. An AI feature called Seer proposes a code fix and reviews pull requests, sold as a paid add on. It supports more than 100 languages and frameworks, from browser JavaScript to backend languages to mobile and game consoles. The code is public under the Functional Source License, which allows self hosting but not reselling and converts to an open license after two years. Pricing has a free Developer plan for one user and a small monthly error allowance, then Team and Business plans. Billing is usage based, with errors, tracing spans, replays, logs, and attachments each carrying its own quota and its own overage rate.
Limitations
The quota system is the main frustration. Errors, spans, replays, and other event types each have a separate allowance, and it takes time to learn what counts and how fast it drains. A backend service stuck in an error loop can burn a month's quota in hours. Once a quota is hit on the free plan, new events are simply dropped, so you lose data at the worst moment. Costs are volume based and tied to how many errors an app produces, which is variable and often outside a team's control, so bills are hard to predict. Setting a spending cap helps, but hitting the cap also stops event collection. The jumps between plan tiers feel steep for small teams, and session replay needs paid add ons beyond a small included amount.
Insight
Sentry is the standard tool for catching errors in production, and it earns that. When something breaks, it usually gives a developer enough to reproduce and fix it without guesswork, and the grouping keeps a single bug from burying the dashboard. It has also expanded into tracing, replay, and profiling, which are decent but not the reason most teams are there. The recurring pain is the quota model. Every event type meters separately, a noisy service can drain the allowance fast, and when you run out the tool stops collecting right when you need it. Spending caps have the same catch. Teams should tune what they send, filter noisy errors early, and keep an eye on the quota rather than setting it and forgetting it. Best for teams that want reliable error tracking and will do a little upkeep on volume. The self hosted option exists but is real work to run.
Pricing
Freemium
Website
Last checked 2026-08-30