Waitlist API - Quick and easy waitlist with built in referral.
API List - A collective list of APIs. Build something.
API Tracker - Application and Data, Application Utilities, and API Tools
Phantombuster - A marketplace of simple to use no-code APIs
Dwolla - Dwolla powers innovations with sophisticated account-to-account payment solutions.
The Unsplash API - No-limits, do-what-you-want API for access to 200K+ HD pics.