pump.io : Social server with an ActivityStreams API. It's a stream server that does most of what people really want from a social network.
Strapi : Open source Node.js Headless CMS to easily build customisable APIs
TYPO3 : TYPO3 is an enterprise-class, Open Source CMS (Content Management System), used internationally to build and manage websites of all types, from small ...
Data Science Toolkit : A collection of the best open data sets and open-source tools for data science, wrapped in an easy-to-use REST/JSON API with command line, Python and ...
Simple Content Platform to manage any structured content.
A self-hosted headless and api-driven CMS.