Open DBDiff - A database comparison tool for Microsoft SQL Server 2005+ that reports schema differences and...
DBeaver - DBeaver - Universal Database Manager and SQL Client.
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
FlameRobin - FlameRobin is a cross-platform, open-source database administration tool for Firebird DBMS.
MssqlMerge - MssqlMerge is an easy to use diff & merge tool for Microsoft SQL Server databases.
RazorSQL - RazorSQL is an SQL Editor and SQL database query tool for macOS, Windows, Linux, and Mac OS X.