e4mc: The Mod That Puts Your World Online for Free

e4mc is a free, open-source mod that takes the world you already play in and gives it a public address while your game is open. Only you install it. Your friends paste the address into the normal multiplayer screen, on a completely vanilla copy of Minecraft, and they are in.

What is e4mc?

e4mc is a client-side Minecraft mod by vgskye. It hooks into Open to LAN — the feature that normally only shares your world with people on the same Wi-Fi — and gives that world a public address instead, something like abcdef.e4mc.link.

It is free, open source, and needs no account, no subscription and no router settings. What it is not is a hosting service: your world runs on your computer and is reachable only while your game is open.

How does e4mc work?

When you open your world to LAN, the mod connects out to one of e4mc's relay servers over QUIC, a modern transport protocol that rides on UDP. Your router already allows outbound connections, so nothing has to be opened or forwarded. The relay is handed a public hostname, and traffic from your friends is passed back down that same connection to your game.

Since version 6.0.0 the mod also includes Dialtone, a peer-to-peer layer. When the person joining also happens to have e4mc installed, the two computers can connect directly instead of going through the relay, which cuts out a hop. Friends without the mod simply use the relay, which is the normal case.

Two consequences are worth understanding before you rely on it. Because the connection is outbound, e4mc works behind CGNAT, where port forwarding cannot work at all. And because the traffic is QUIC over UDP, a network that blocks UDP or QUIC — some school, campus and workplace networks do — can stop it from connecting.

How to use e4mc

e4mc is Java Edition only, and runs on Fabric, Quilt, Forge and NeoForge. Pick whichever loader you already use.

1. Install a mod loader

   Install Fabric or NeoForge for your Minecraft version, then create a launcher profile that uses it. If you already play modded, you have this.

2. Download e4mc

   Get the build that matches both your loader and your Minecraft version from Modrinth or CurseForge. On Fabric you will also need Fabric API.

3. Drop it in the mods folder

   Put the .jar into .minecraft/mods. On Windows, paste %appdata%\.minecraft\mods into the address bar of File Explorer to get there.

4. Load your world

   Start the game on that profile and open the single-player world you want to share.

5. Open to LAN

   Press Esc, choose Open to LAN, set the game mode and whether cheats are allowed, then choose Start LAN World.

   Open to LANStart LAN World

6. Copy the address

   Chat prints a public address ending in e4mc.link alongside the usual LAN port, and copies it to your clipboard. Send that to your friends.

How your friends join

Nothing is installed on their side. They need the same Minecraft version you opened the world on, and the address.

1. Match the version

   In the launcher, select the same Minecraft version you are hosting on. They do not need your mod loader or any mods, unless your world itself uses content mods.

2. Add the server

   Choose Multiplayer, then Add Server, give it any name, and paste the e4mc.link address into Server Address.

   MultiplayerAdd Server

3. Join

   Save it and choose Join Server. Do not add a port — the address already carries everything needed.

   Join Server

e4mc commands

With cheats enabled, e4mc adds a small command set. /e4mc doctor is the one to remember — it is what the mod's author asks for when someone reports a problem.

Keep strangers out of your world

This is the part most e4mc tutorials skip, and it matters. A LAN world has no whitelist and no ban list by default, because Mojang never expected one to be reachable from the internet. While your session is live, anyone holding the address can walk in.

In practice addresses do leak — pasted into a public Discord, shared onward by a friend, or left in a screenshot. e4mc has an answer for this: a configuration option (restoreDedicatedCommands) that restores the dedicated-server moderation commands on a LAN world.

• Turn on the dedicated commands in e4mc's config, then use /whitelist on and /whitelist add <name> exactly as you would on a real server. Our whitelist guide covers the full command set.
• Use /ban and /pardon for anyone who turns up uninvited; without the config option, a LAN world gives you neither.
• Share the address privately — a direct message, not a public channel — and remember it changes next session anyway.
• Run /e4mc stop the moment you are done hosting, rather than leaving the session open while you build alone.
• Back up the world first. Anyone who joins can break blocks. Copy the save folder before the first session with new people.

Is e4mc safe?

For the mod itself, the honest answer is yes, with the usual caveats. It is open source, so the code can be read by anyone, and it asks for no account and no payment. The risks are not really about the software:

• Your traffic passes through someone else's relay. Unless Dialtone puts you in a direct connection, your game traffic is relayed by e4mc's infrastructure. That is inherent to how any tunnel works, e4mc included.
• Your world is open to whoever has the address. This is the real risk, and it is the section above, not a flaw in the mod.
• Download it from Modrinth, CurseForge or the project's own repository. Minecraft mods are a well-known malware vector, and reuploads on random sites are where that happens.
• Your home IP is not exposed. Friends connect to the relay hostname, not to you — which is a genuine advantage over port forwarding.

e4mc vs Essential Mod

These are the two mods people compare, and they solve the same problem in opposite ways. The deciding question is whether your friends are willing to install something.

Put simply: e4mc if anyone joining is on vanilla, Essential if your whole group already runs mods and wants the social features. Nothing stops you having both installed and using whichever suits the evening.

Older Minecraft versions: e4mc Retro

The main mod covers modern versions. If you play on something older, a separate community backport called e4mc Retro, by xhyrom, reaches back much further. It is a different project from a different author, so support and releases are separate.

e4mc not working? Common errors

Start here regardless of the symptom: update to the newest e4mc for your version, reproduce the problem, then run /e4mc doctor. That produces the log the author asks for, and it often names the cause outright.

Alternatives to e4mc

e4mc is deliberately narrow: one world, open while you play, Java only. When that is not the shape you need:

• A tunnel service such as playit.gg does the same job for a real server jar, so the world stays up when you are not in it, and works for Bedrock too.
• A private network app such as Tailscale is stricter — nothing is published publicly at all — at the cost of everyone installing it.
• Essential Mod if your whole group is modded and wants invites instead of an address.
• A rented host or Realms when the world needs to run while your computer is off.

Our guide to playing with friends without a server compares all of these side by side. When your world outgrows a laptop and becomes something you want people to find, make it a proper server and list it publicly.