Opta - Opta is a new kind of Infrastructure-As-Code framework designed for fast moving startups.
Uppy - The next open source file uploader for web browsers
Chain - The Block Chain API for Developers
Uploadcare - File uploading, media processing & content delivery for modern web apps
Cal.com - Cal.com (formerly Calendso) is the open source Calendly alternative.
Filestack - Simple file uploader and robust APIs for uploading, transforming, and delivering any file into your app. Filestack is a collection of tools and powerful APIs that make it simple to upload, transform, and deliver content.