The modding community is incredibly active, with new updates being released constantly. Here are a few popular mods confirmed to have recent updates and downloads available outside of Steam:
Once you find a mod on a website like Modding of Isaac, GitHub, or Skymods, download it. The file will usually be a .zip or .rar archive. Use a free tool like 7-Zip or WinRAR to extract its contents. Inside, you should find a folder containing the mod's code, graphics, and a metadata.xml file. the binding of isaac repentance mods no steam updated