Redis - Redis is an open source in-memory data structure project implementing a distributed, in-memory key-value database with optional durability.
DBeaver - DBeaver - Universal Database Manager and SQL Client.
SQLite - SQLite Home Page
DataGrip - Tool for SQL and databases
PouchDB - Open-source JavaScript database inspired by Apache CouchDB that's designed to run well within the browser
HeidiSQL - HeidiSQL is a powerful and easy client for MySQL, MariaDB, Microsoft SQL Server and PostgreSQL. Open source and entirely free to use.