Thanos.io - Open source, highly available Prometheus setup with long term storage capabilities.
Rainmaker - Rainmaker allows you to make your Google Contacts better.
Stripe - Online payment processing for internet businesses. Stripe is a suite of payment APIs that powers commerce for online businesses of all sizes. Use Stripe’s payment platform to accept and process payments online for easy-to-use commerce solutions.
OpenTracing - Consistent, expressive, vendor-neutral APIs for distributed tracing and context propagation.
dip - accountability groups for developers
OpenCensus - Application and Data, Monitoring, and Monitoring Tools