Sentry is an error-tracking and application monitoring platform made by Functional Software, Inc. It collects errors, logs, traces, session replays, profiles and metrics from a running application and connects them through distributed tracing (a record of one request as it passes through all the services). Sentry started as an open-source project.
A developer adds the Sentry SDK, a small library, to the application with a few lines of code; official SDKs exist for JavaScript, Python, Go, Java, Swift, mobile frameworks and game engines. Sentry captures unhandled exceptions automatically and groups similar errors into issues, each with its stack trace and the suspect commit that probably caused it. Session Replay shows a video-like reproduction of what the user did before an error, and profiling shows which functions are slow in production. Seer, an AI debugging agent, uses this data to explain the cause and to propose a fix. Integrations connect Sentry to GitHub, Slack and Jira.
Sentry is a hosted service. A free plan covers one user; paid plans are billed each month, with extra events charged by volume. Its source code is public on GitHub.