Dashblock - Turn any website into an API
Slack Events API - Subscribe to events in Slack via HTTP
Sheety - Turn any Google sheet into an API instantly, for free. Power websites, apps, or whatever you like, all from a spreadsheet. Changes to your spreadsheet update your API in realtime. Neat
B12 Bookings - Bookings scheduling software that integrates with your site
Postman - The Collaboration Platform for API Development
Guestboard - Lead powerfully-organized group events with Guestboard – a modular event platform that gives groups of 10-1000+ people a central space to coordinate, build excitement, and save money. No more crazy email threads. No more massive group texts.