The Mod Tools for Dawn of War are released by Relic, first released on the 10th of November 2004, and usually after each patch which changes how they work. They only work on windows (Supports versions 2000 and XP), and only when you meet the games requirements. They also have no liability when you install them – if they don't work, they don't work, limited testing of the tools has been carried out (although bugs get fixed in time). Currently the mod tools are still being released/updated, since Relic have an expansion coming out.
The current version of the Relic Dawn of War Modtools is 1.11. (Archive page here)
The current version of Dawn of War is 1.3. Patch notes
Current Dawn of War tools release notes can be found here: