Sentry

Sentry tracks errors and performance problems in websites, apps and servers. Add a Sentry SDK (available for JavaScript, PHP, Python, Java, Go, iOS, Android and many more) and every crash or exception is reported with its stack trace, the browser or device, and the steps that led up to it, with alerts by e-mail. It also offers tracing, session replays, logs, and uptime and cron monitoring. The Developer plan is free forever for one user with 5,000 errors; the management API, integrations and more users need a paid plan.