Drawpile is available for Windows in 32 and 64 bit versions. If you encounter problems with the 64 bit version, try the 32 bit version also. Windows Vista and XP are only supported by the 32 bit version.
Minimum supported OSX version is 10.7.
Note. Because I'm not a registered Apple developer, this package is not signed. If you get a message saying the application cannot be opened because it is from an unidentified developer, you must add an exception for it. Right click on the app and select Open. You should now see the dialog again with the option to open the application anyway. After this, macOS will remember your choice and not show the warning for this application.
If the current version is not available in your distribution's repositories, you can use the AppImages provided here.
The dedicated server is packaged separately. Note that the server AppImage at the moment does not include the GUI. It is suitable for use on headless servers.
Drawpile source code is available under the GPLv3 license.
The latest development version (and all past releases) can be found at GitHub.
Check the version compatibility chart to see if you need to use an old version.
Previous stable release:
More old releases can be found in the release archive. All releases are also tagged in the Git repository.