Horizon servers start with a flag.
Seventeen packs pass it.
Every pack in the catalog says whether it belongs on a server. This page explains what the flag covers, how to start a server for friends, and which client mods a server owner is entitled to reject.
A pack is client-side. A server is a process.
The pack you install configures the client: HUD, map, recipe viewer, camera. A Horizon server is a separate process started from the game install. It reads server.properties, listens on one port, and keeps the world.
The xHorizon launcher can start and stop that process, edit the properties file, stream the console and ping the port over TCP. It does not rent hardware for you and does not create a public address out of nothing. If the port is closed on your router, the server is still local.
This split is why the server-safe flag exists. A pack that changes movement or adds reactors can be fine in single-player and still be a bad default on someone else's server.
17 safe, 3 solo.
The flag answers one question: would a server owner be surprised by what this pack adds? It is not a guarantee that every server accepts it.
| Pack | Marked | Why |
|---|---|---|
| High Voltage | solo + LAN | Reactors, missiles and orbital strikes. Fine at home, a different game on a shared server. |
| Drift | solo + LAN | Flight, wall running and web swinging change movement in ways a server cannot verify. |
| Any% | solo + LAN | A speedrun timer and a thin HUD built for single-player attempts. |
- That the server owner runs the same pack. They may run none.
- That a client mod is welcome. Voice chat and server browsers are still client software.
- That the pack is allowed on a public competitive server. Their rules come first.
Host for friends
Pick a server-safe pack
Hearth for survival, Campfire for voice and a server list, Duel if the point is fights. All three are flagged safe.
Start the server process
From the Servers screen. The launcher writes the profile, starts the process and shows the console from the first line.
Open one port
Set the port in server.properties. Try UPnP first; when the router refuses, forward the port by hand. The launcher tells you which happened.
Give friends the address
Address and port, nothing else. Each friend signs in with their own Microsoft account that owns Java Edition.
What friends need installed
Their own copy of Horizon 26.3 and their own Java Edition account. After that it depends on the pack: a pack that adds blocks, ores or machines changes world data, so both sides need the same manifest. A pack that only adds HUD, maps or a camera stays on the client, and a friend can join without it.
Voice chat is a client mod. It works when the server allows it and when the friend installs it too; it is not a feature of the server process. Chat heads and the server browser are the same story.
RAM, distance and the first night
Eight gigabytes is the floor for a small server; sixteen is comfortable if the pack carries Distant Horizons or a large AE2 base. View distance costs more than player count in most small sessions, so lower it before you add hardware.
Start with two players and one night. If the console is clean and the world saves on stop, the setup works; everything after that is preference.
Public servers and mods that get you removed
X To Xray, Baritone, SeedCrackerX and I'm Fast are ban material on most public servers. ViaHorizon targets offline-mode servers and does not belong on a server that checks accounts. None of them appears in a public pack here; I'm Fast appears in one single-player pack with the limit on the card.
This is the server owner's call, not ours. A client mod that removes a check is a reason to be removed, and no catalog can change that.
Before the first join.
Play with friends
The full route: one host, one port, the same game version, and what to check when a friend cannot connect.
guideWhich pack for a group
Hearth, Campfire and Duel are built for shared worlds. The table maps a goal to a pack.
17 safeClient mods that stay client-side
HUD, map and camera mods do not change world data. Content packs do. The difference decides who installs what.
144 modsServer listings from the community live on the servers page. Submissions go by email until the form ships.
Questions this page gets
Can I play a modpack on a Horizon server?
Yes, if the pack is marked server-safe. Seventeen of the 20 are. High Voltage, Drift and Any% are flagged solo and LAN because of reactors, flight and a speedrun timer; the card says so before you download.
Do my friends need the same pack?
If the pack adds blocks, ores or machines, yes: both sides have to agree on the world data. HUD, map and camera mods live on the client, so a friend can join without them.
Does the launcher host a server for me?
It starts and stops a server process, edits server.properties, shows the console and pings the port. It does not rent hardware or give you a public address; that part is your machine or your host.
Why does UPnP fail?
Because the router has it off, or the router implements it partially. The launcher reports when UPnP is not available instead of pretending the port is open. Forward the port by hand in that case.
Can I invite friends with a code?
Not yet. Invite codes are planned but not shipped in 0.1.4. For now you share the address and port, or use a LAN session, and the server owner manages who joins.
One host, one port, one pack.
Pick a server-safe pack, start the process, forward the port. Seventeen packs are ready for that; three are marked solo and say why.