GoAccess.io - open source real-time web log analyzer and interactive viewer that runs in a terminal in *nix systems or through your browser.
DO_Snapshot - command-line snapshot maker for your DigitalOcean droplets.
MetaBase is the easy, open source way for everyone in your company to ask questions and learn from data.
MailHog - Web and API based SMTP testing, inspired by MailCatcher
Localstack - a fully functional local AWS cloud stack. Develop and test your cloud apps offline!