DBeaver - DBeaver - Universal Database Manager and SQL Client.
Dataedo - Database documentation tool
SQuirreL SQL - SQuirreL SQL is an open-source Java SQL Client program for any JDBC compliant database
DBComparer - Free Compare database tool - DBComparer 3.0 is a professional compare database tool for comparing Microsoft SQL Server 2008 (and 2005) database structure.
ApexSQL Doc - ApexSQL Doc creates database documentation in a variety of formats.
HeidiSQL - HeidiSQL is a powerful and easy client for MySQL, MariaDB, Microsoft SQL Server and PostgreSQL. Open source and entirely free to use.