LogTailApp - LogTail is a local and remote (SSH) log file viewer and monitoring application for Mac OS X. It is a pure, modern, document-based Cocoa App
Google Open Source - All of Googles open source projects under a single umbrella
AppSignal - We monitor the software that makes your customers happy.
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.
Open Source @IFTTT - A collection of IFTTT OSS projects.