DBeaver - DBeaver - Universal Database Manager and SQL Client.
Open DBDiff - A database comparison tool for Microsoft SQL Server 2005+ that reports schema differences and...
MySQL Workbench - MySQL Workbench is a unified visual tool for database architects, developers, and DBAs.
Redgate SQL Data Compare - Use Redgate SQL Data Compare to compare and synchronize static, lookup, and reference data in your SQL Server database - try it free
HeidiSQL - HeidiSQL is a powerful and easy client for MySQL, MariaDB, Microsoft SQL Server and PostgreSQL. Open source and entirely free to use.
DBComparer - Free Compare database tool - DBComparer 3.0 is a professional compare database tool for comparing Microsoft SQL Server 2008 (and 2005) database structure.