SQL Server Tools

• BI Helper:
• Hex Editor:
• Process explorer: 
• SQL Sentry Plan Explorer:
• Brent Ozar’s Favorite Free Tools

MySQL Tools

• Percona toolkit:  is a collection of advanced command-line tools used by Percona support staff to perform a variety of MySQL and system tasks that are too difficult or complex to perform manually.
• Jet Profiler:  is a real-time query performance and diagnostics tool for the MySQL database server. It’s core features:
  • Query, table and user performance
  • Graphical visualisation
  • Low overhead
  • User friendly