Google Cloud PostgreSQL - Fully-managed database service
PopSQL - Modern SQL editor for teams
Supabase - An open source Firebase alternative
SQL Police Department - Learn SQL while solving crimes! Climb the ranks of SQL PD.
pganalyze Index Advisor for Postgres - The index advisor makes recommendations for creating the best indexes for your Postgres queries, based on the schema and table statistics information.
DrawSQL - Easy database diagrams. Create, visualize and collaborate on your database entity relationship diagrams.