Sentry watches your application for exceptions and slowdowns, groups them into issues, and ties them to the release and commit that introduced them. SDKs cover practically every language and framework, and tracing, profiling and session replay have grown it from error tracker into an observability suite for application code.
It suits any team shipping code users depend on — the free tier fits side projects, and self-hosting is possible for the committed. The main discipline is cost: high-volume events and replays need sampling policies before the bill surprises you.