"Mods" and "plugins" sound interchangeable, but they aren't — and mixing them up is the number-one reason a modded server won't start. This guide sorts out the difference first, then walks through the Mods and Modpacks pages.
| At a glance | |
|---|---|
| You need | A Minecraft server, and players willing to install things too |
| Time | Fifteen minutes for a single mod; longer for a full pack |
| Modpacks | Need a bit more — noted in that section |
Mods vs plugins — the difference that matters
A plugin runs only on the server. Players join with a totally normal, unmodified Minecraft client — they never install anything. That's why plugins are the easy path (see Essential plugins).
A mod is different. Most content mods — new blocks, mobs, dimensions, machines — change the game itself, so they must be installed on both the server and every player's client, with matching versions. If your friends don't have the same mods, they can't join. There are server-side-only mods (performance boosters, some utilities) that players don't need locally, but assume a content mod is a both-sides job unless it clearly says otherwise. Tell your players before you build a modded world.
Mods also need a mod loader as the base software — plugins and mods aren't interchangeable and (mostly) don't run on the same server.
| Plugin | Mod | |
|---|---|---|
| Runs on | Server only | Server + every player's client |
| Players install | Nothing | Matching mods, matching versions |
| Base software | Bukkit family (Paper, Purpur…) | A mod loader (Fabric, Forge…) |
1. Pick a mod loader
Open the Version Changer (from the Console) and choose a Mod Loader: Fabric, Forge, Quilt, or NeoForge. Which one? Whatever your mods are built for — a mod's download page always says. Fabric (lightweight, fast-updating) and Forge (huge back-catalog) are the two you'll meet most. See Minecraft software and versions if you're switching.
2. Install mods from the Mods page
Open the Mods page from your server menu. Its search pulls from Modrinth and CurseForge and is filtered to your loader, so you only see mods that actually fit — no guessing about compatibility. Find a mod, press Install, and it lands in your server's /mods folder. Repeat for each mod you want.
3. Restart
Like plugins, mods load at startup. Restart from the Console and watch the log — the loader lists mods as it brings them up, and complains loudly if two of them disagree.
Modpacks: a whole pack at once
Building a big pack mod-by-mod is tedious. The Modpacks page installs a curated pack — all its mods and configs together — from Modrinth, CurseForge, FTB, and Technic. Search the pack, install, restart, and the server side is done.
Two honest notes:
⚠️ Heads up: The one-click Modpacks installer is a premium feature for free-plan servers created after 2026-03-24. Installing individual mods from the Mods page stays free.
- It's a premium feature for free-plan servers created after 2026-03-24. If your free server is newer than that date, the Modpacks page prompts you to upgrade. (Installing individual mods from the Mods page stays available on free; premium unlocks the one-click full-pack installer.)
- Your players need the matching pack too. A modpack is a both-sides thing, same as any content mods. The cleanest route for players is the pack's own launcher — CurseForge, Modrinth, FTB, or Technic — which installs the exact pack and version in a couple of clicks. Point players at the pack's official launcher instructions; matching versions is what makes joining "just work."
Updating and removing mods
Mods show up in the Mods page's My Addons view just like plugins do: it flags any with a newer build available and gives you an Update button (update one at a time, then restart), plus a toggle to disable a mod without deleting it — handy for isolating a bad one. To remove a mod for good, delete its .jar from the /mods folder in the File Manager and restart. Remember that mods are a both-sides deal, so if you update or remove a content mod, your players need to match the change or they can't rejoin.
When a mod crashes
Modded Minecraft crashes more than vanilla — a single incompatible mod can take the whole server down at boot. When it happens, the Minecraft console's crash helper reads the crash and can disable the offending file in /mods for you, so you can start back up and try again. Add mods in small batches so a crash points at a short list of suspects.
A word on RAM
Mods are hungry. Every one loads assets and runs logic, and a big pack can want several gigabytes just to reach the main menu. The free plan's 2.5 GB shared RAM is genuinely tight for large packs — a lightweight Fabric setup is fine; a 200-mod kitchen-sink pack often isn't.
🎯 Good to know: The free plan's 2.5 GB shared RAM is genuinely tight for large packs — a lightweight Fabric setup is fine; a 200-mod kitchen-sink pack often isn't. If a modded server keeps getting killed, that's memory: see Performance and lag and the out-of-memory guide.
Troubleshooting
- Won't start after adding mods — a mod conflict or a missing dependency. Read the console; the crash helper can disable the culprit in
/mods. Many mods need a library mod (Fabric API is the classic) — install that too. - Players can't join a modded server — they don't have the matching mods/pack, or their versions differ. Everyone needs the same loader, mods, and Minecraft version.
- Killed on startup with a big pack — out of RAM. See the section above.
Next steps
- Minecraft software and versions
- Performance and lag
- Manage your Minecraft worlds
- See the Knowledge Base: mods and modpacks.