Yeah it is, but there are some rules for that as:

• Everyone in the lobby needs to have the same core mod loader (BepInEx from Thunderstore).
  
  
• If you’re all running the same mod list (same mods + same versions), the game should sync fine.
  
  
• If players have different mods:
  
  
• Cosmetic/quality-of-life mods (like UI changes, extra info) usually don’t cause issues.
  
  
• Gameplay-altering mods (new monsters, tools, balance tweaks) must be identical for all players, otherwise you’ll likely get errors or desyncs.

For that I reccomend Thunderstore because it makes this easier!

• You can create a profile in Thunderstore Mod Manager that contains all your installed mods.
  
  
• Share that profile code or export file with your friends → they can import it and instantly get the exact same setup.
  
  
• This ensures everyone has identical versions, avoiding crashes or mismatches.

Well as i mentioned before we will talk about Thunderstore Mod Manager:

• Step 1 – Create a Profile:
  
  
• Open Thunderstore Mod Manager.
  
  
• Select R.E.P.O. from your installed games.
  
  
• In the top left, click Profiles → Create new profile (give it a name ”repo mod blah blah” ).
  
  
• Install all the mods you want into that profile.
  
  
  
• Step 2 – Export Your Profile:
  
  
• With your profile selected, click the Profile Options button (three dots ⋮ or gear icon).
  
  
• Choose Export profile → it will generate a .zip file or a profile code:
  zip method: send that .zip file to your friends.
  Code method: Thunderstore gives you a shareable string of text (like thunderstore://profile/...).
  
  
• Step 3 – Friends Import Your Profile:
  
  
• Your friends open Thunderstore Mod Manager.
  
  
• Go to Profiles → Import profile.
  
  
• They either:
  Select the .zip file you sent.
  Or paste the profile code into the import box.
  
  
• Step 4 – Launch the Game Together
  
  
• Everyone selects the same imported profile.
  
  
• Click Modded Launch in Thunderstore.
  
  
• You’re now all running the exact same mods and can join each other’s games without issues.

If something may not work as suggested it may be my fault and I deeply a apologize for it, it was hard for me to lean this too. If you may have question feel free to ask in the comments and i will probably respond in a few days! If i dont seem to answer or my answer is not good enough please google it yourself!

you can find modes in Thunderstore Mod Manager, you have some dediacted pages there. I will also paste some YT videos that explain these things. Thank you for understanding.

Core (Required)

• BepInExPack for R.E.P.O.
  
  
  The framework that lets all other mods work.
  Install this first — nothing else works without it.
  
  
• Quality of life:
  
  
• More Info HUD
  
  Adds extra UI info: timers, loot status, monster warnings, etc.
  
  Super helpful in co-op so everyone knows what’s going on.
  
  
• Ping System:
  Lets you mark locations/objects.
  
  Great for quick communication without relying only on voice chat.
  
  
• Better Flashlight:
  Makes your flashlight brighter and less annoying.
  
  Small tweak, big difference for exploring dark maps.
  
  
• Fun / Cosmetic
  
  
• Silly Sounds Pack
  
  Replaces some sound effects with goofy ones (optional but hilarious in co-op).
  
  
• Custom Skins / Outfits
  
  Simple character reskins (can be funny or stylish).
  
  Purely cosmetic — no gameplay effect.
  
  Gameplay (Optional, consult with your friends, or dont. You know the ”What is that?” line):
  
  
• Extra Monsters
  
  Adds a few new enemy types for variety.
  
  Only use this if your group wants extra challenge.
  
  
• Loot Tweaks
  
  Makes loot physics a bit less punishing (items won’t break as easily).
  
  Good if you want a slightly more forgiving experience.

Fistly Thunderstore: https://thunderstore.io/c/repo (paste this in the url bar)

Then we have the YT tutorials

https://www.youtube.com/watch?v=4USGwHvdmeE

https://www.youtube.com/watch?v=YS3LthyB8x8

https://www.youtube.com/watch?v=_dvj4ypRmbw

https://www.youtube.com/watch?v=W93KHD6t0BQ

https://www.youtube.com/watch?v=NClkdOJbigQ

https://www.youtube.com/watch?v=UA4TGpMHm0Q

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3482445695

I hope that now you are ready to play REPO with mods. Consider rating this guide and maybe treating me with an award!