ArangoDB is a distributed free and open-source database with a flexible data model for documents, graphs, and key-values. Build high performance applications using a convenient SQL-like query language or JavaScript extensions. (Apache)
Cross-platform
CouchDB is a database that completely embraces the web. Store your data with JSON documents. Access your documents with your web browser, via HTTP. Query, combine, and transform your documents with JavaScript. (Apache)
Cross-platform
eXist-db is an open source database management system entirely built on XML technology. It stores XML data according to the XML data model and features efficient, index-based XQuery processing. (LGPL)
Cross-platform
MongoDB is a scalable, high-performance, open source, document-oriented database. The database is document-oriented so it manages collections of JSON-like documents. (AGPL)
Linux - FreeBSD - Windows - macOS
Redis is an open source, BSD licensed, advanced key-value store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets. (BSD)
Cross-platform
RethinkDB is built to store JSON documents, and scale to multiple machines with very little effort. It has a pleasant query language that supports really useful queries like table joins and group by, and is easy to setup and learn. (AGPL)
Cross-platform
SpiceDB is the most scalable and consistent Google Zanzibar-inspired database for storing and computing permissions data—use it to build global-scale fine grained authorization services. (Apache)
Cross-platform
7 applications