I'm a consultant/engineer in databases
area. I work mainly on Oracle Database RDBMS
(but I've also some experience on Sybase, MySQL...). I'm
mainly specialized on Administration (DBA) and Performance (Tuning)
areas...
Despite it is better to use only professional software
in a professional environment some freeware can be useful
for certain non critical purposes like testing, training...
The following are my favorites to work with Oracle (or other databases) or some I've heard they are worth to test :
An open source visual text file differencing and merging tool for Windows. It is highly useful for determing what changes between files (like tkprof...).
A free graphical tool (from and so for Oracle) that "enhances productivity and simplifies database development tasks". It allows to browse database objects, run SQL statements and SQL scripts, and edit and debug PL/SQL statements. Probably a future serious concurrent of TOAD..