Slack SQL
PopSQL
DrawSQL
Numeracy
AI2sql
SeekWell
Cogram
SQLizer API
SQL Teaching
SQLBolt
SQLZOO
PostgreSQL Exercises
Select Star SQL
Programming Hub
Secoda
PopSQL - Modern SQL editor for teams
SQLBolt - SQLBolt provides a set of interactive lessons and exercises to help you learn SQL
DrawSQL - Easy database diagrams. Create, visualize and collaborate on your database entity relationship diagrams.
SQLZOO - SQLZoo includes tutorials and reference to support people learning SQL. It features:
Numeracy - A SQL pad that gives you x-ray vision for your data
PostgreSQL Exercises - Education & Reference