Startup School - How to start a startup, by Y Combinator
The Y Combinator Database - The definitive database of YC companies with all the metrics
Electron Toolkit - Toolkit to build and launch Electron apps
Y Combinator Companies - Interactive list of all 1000+ YC companies
Rippling - One directory for employee information across IT, HR, legal, finance and facilities.
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.