UserGuiding - Create in-app experiences with the most straightforward product adoption platform — quick implementation, lasting user engagement.
The Y Combinator Database - The definitive database of YC companies with all the metrics
Usetiful - Fight user churn with great user onboarding. Interactive product tours and smart tips significantly improve your user retention.
Startup School - How to start a startup, by Y Combinator
Userlane - Digital adoption platform with interactive guidance for software applications allowing anyone to understand and master any software from the get-go.
Apply to YC (Y Combinator) - Curated collection of resources for founders applying to YC.