A Minecraft proxy built for modded servers
Kojacoord is the Rust proxy that runs KojaCraft. We needed something that could handle serious modded servers, so we built it ourselves — and it's free and open source.
How it works
One endpoint in front of your whole network
Kojacoord sits between clients and your backend servers, handling protocol, auth, routing, and plugins so each server can focus on running the game.
Players connect
Clients on different Minecraft versions connect to one Kojacoord address — no mods needed on the client side.
Kojacoord handles the rest
The proxy handles protocol translation, auth, and routing, then sends players to the right server — plugins can hook in along the way.
Backends do what they do best
Your modded servers get clean traffic and can be restarted or swapped without disconnecting players.
Use cases
What you can build with Kojacoord
The same tech that powers KojaCraft — packaged for your own servers.
Modded networks
Full FML handshake support (FML1 through FML2/FML3), so modpack servers can run behind one proxy without breaking client mods.
Multi-version support
Accept clients from 1.6.4 to the latest release, with protocol conversion handled automatically during relay.
Edge protection
Per-IP connection throttling and a pluggable IP-reputation blocklist stop abusive traffic before it reaches your backends.
WASM plugin system
Write plugins in Rust against the typed guest SDK — hook joins, chat, server switches, and more, with Redis and outbound HTTP access.
Online & offline auth
Full Mojang auth with profile-signature verification, or offline mode for private servers and dev setups.
Hot-swapping
Failover groups with automatic failback and a limbo holding world mean backends can restart without disconnecting anyone.
Prometheus metrics
A read-only metrics endpoint for real-time visibility — no admin HTTP surface, no database, nothing else listening.
Hot config reload
Edit config.toml and most changes apply live, no restart and no dropped connections.
What's next for Kojacoord
Shipped, in progress, and planned — pulled live from ROADMAP.md in the repo.
Global metrics
Kojacoord network overview
Anonymous usage data from proxies with telemetry enabled — served from metrics.kojacraft.net. No IPs, server names, or player data. Operators can opt out with one config line.
Privacy-first and opt-out by default.
Anonymous metrics, fully opt-out
Kojacoord can send anonymous usage metrics to metrics.kojacraft.net so we can understand adoption and prioritise work. It is designed to be privacy-preserving, and you can turn it off completely.
Opt out in your proxy config:
[telemetry]
# Set to false to disable all anonymous metrics.
enabled = falseWhen disabled, the proxy never contacts the metrics endpoint.
What we collect
- Anonymous, randomly-generated instance ID (hashed, rotates)
- Proxy version and operating system
- Aggregate counts: online player peak, backend count
What we never collect
- ✕IP addresses or hostnames
- ✕Server names, MOTDs or player identities
- ✕Plugin contents, chat or world data
Community
Built by contributors
Kojacoord is open source. These are the people shipping it.