List of free SQL stuff for developerππ½
If you're looking for all programming tools around SQL (not just free). Check this page List of SQL Programming Tools

SQLite Viewer Web App
A free online SQLite Explorer, inspired by DB Browser for SQLite and Airtable. Use this web-based SQLite Tool to quickly and easily inspect sqlite files on the web.
Tag: sql, playground

Flatbase
Query your CSV and JSON files with SQL. Flatbase is the data science platform for developers. Upload files, write SQL, visualize results, and share with collaborators.
Tag: sql, json, api, playground
Up to 3 workspaces Share with up to 3 teammates
HeidiSQL - MariaDB, MySQL, MSSQL, PostgreSQL and SQLite made easy
HeidiSQL is a free and powerful client for MariaDB, MySQL, Microsoft SQL Server, PostgreSQL and SQLite
Tag: database-gui, sql, nosql
Open Source Only for Windows
Dolt | Git for Data
Dolt β It's Git for Data. Contribute to dolthub/dolt development by creating an account on GitHub.
Tag: sql, git, version, data
Is a open source project only (for now) MySQL support

Sequel Ace
Sequel Ace is a fast, easy-to-use Mac database management application for working with MySQL & MariaDB databases.
Tag: sql, database
Mac OS X only

Format Express
Instant online formatter for JSON / XML / SQL : what you paste is immediately beautified with syntax highlighting, node navigation, minimap, search tools, ...
Tag: json, xml, sql, formatter
Illimited use. No ads, no tracking.
Directus
Open-Source Data Platform β Directus wraps any SQL database with a real-time GraphQL+REST API and an intuitive app for non-technical users. 100% JavaScript.
Tag: Database, SQL, GraphQL, API, CMS
Completely Free and Open-Source Works with any New or Existing SQL Database REST & GraphQL API Powerful Content/Data/Asset Management Completely Flexible Content Structure