RRDTool
Description: RRDTool is open source software for logging and graphing time-series data. It is useful for monitoring server and network statistics over time.
Type: software
Pricing: Open Source
Sentry
Description: Sentry is an open-source error monitoring system that helps developers monitor and fix crashes in real time. It provides full stacktraces and context on bugs or errors in web apps, mobile apps, games, and APIs.
Type: software
Pricing: Freemium