To download mods from our Modding of Isaac website, you need to own The Binding of Isaac: Rebirth on Steam. You do not need to own any DLCs. You will need to have your Game details and My profile settings set to Public when you log in (you may set them back to the original settings after logging into the site). If you have tried to download a mod when you own the game and weren't allowed to, try logging out and back in again. If that does not work, use the discussions boards or Discord server.
After you have downloaded a mod, it will be in either .zip, .rar, or .7z format. To open this, you need a program such as WinRAR or 7-Zip to open it.
Extract the file(s) into your resources folder. You can find this folder by right click on The Binding of Isaac: Rebirth in your Steam Library, and go to Properties -> Local files -> Browse local files...
Some mods made use non-standard installation methods. Check the mod page for installation instructions.
The default installation location for Windows:
C:/Program Files (x86)/Steam/SteamApps/common/The Binding of Isaac Rebirth/resources/
The default installation location for Mac:
~/Library/Application Support/Steam/SteamApps/common/the binding of isaac/The Binding Of Isaac.app/Content/Resources/resources/
Some mods are easier to uninstall than others. If you still have the original mod package, find the files included in the zip/rar/7z, and delete those files from your resources folder.
I installed a mod and it didn't work!
If you installed a mod and it had no effect or resulted in crashes, go back and make sure you installed it properly. Check the description of the mod and the comments of the mod to ensure that nobody has posted a fix to your issue. Leave a comment on the mod describing your issue and hopefully the author will get back to you. If they don't reply, it is likely the mod is outdated or the author is gone.
Can I mod my game and still get achievements?
When modding files on Rebirth and Afterbirth, achievements will not be disabled. However, when using an Afterbirth+ or Repentance mod, your achievements will be disabled until you've defeated Mom at least once.