Rollbar is an error tracking service from Rollbar Inc. It collects the errors (exceptions) that an application throws while it runs in production and reports them to the developers. Rollbar calls this code-first observability, because it starts from the code that runs in production.
A developer installs a Rollbar SDK, a small library, in the application; SDKs exist for JavaScript, Python, Rails, Java, .NET, Node.js, PHP and other platforms. Each error goes to Rollbar's servers, which group similar errors into one item, send an alert in real time and show the stack trace (the chain of function calls that led to the error) down to the line of code. Session Replay shows what the user did before the error, and deploy tracking ties each error to the release it came from. An AI agent called Resolve reads the code around a chosen error, writes a fix in an isolated environment, runs the tests and opens a pull request for review.
Rollbar is a hosted service. A permanent free plan exists; paid plans are billed each month by the volume of error events, session replays and AI credits.