MultiAuth
by azures04
MultiAuth lets a Forge 1.12.2 server accept logins from several authentication services at the same time, such as Mojang and private providers.
What it does
The mod works like the older multi-provider approach: a single server connects to a number of Yggdrasil-style account services, including Mojang's and private ones. A player's login source is detected through custom network packets, so the provider is identified immediately rather than by trying each one in turn. Players who log in through a service are remembered, which shortens later logins.
MultiAuth is installed only on the server and needs nothing on the client side. It is released for Forge with a single game version, 1.12.2, and the latest file is 0.0.2-alpha, published on 2026-01-03 on the alpha channel. The code is available in a public source repository, and an issue tracker is linked from the project. The mod is not open source; it is licensed under Creative Commons Attribution Non Commercial No Derivatives 4.0.
Key features
Multi-Yggdrasil support
The server accepts accounts from several Yggdrasil-style services at once, including Mojang and private providers.
Instant provider identification
Custom network packets tell the server which authentication source a player uses, without trying each service in turn.
Deterministic UUIDs
Each provider's players receive UUIDs generated in a fixed way, so inventories from different providers do not collide.
Duplicate name handling
An optional index alias distinguishes users who share the same name across providers.
Login source caching
The mod remembers which source each player authenticated with, which speeds up later logins.
RSA-verified skins
Skin data is checked with full RSA signature verification from each provider.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Mixed-account servers
A server that hosts both official and private accounts can accept players from each service in one world.
Who it’s for: Server owners running Forge 1.12.2 who want players from more than one authentication service to join the same server. Players only need a normal client, since the mod is server-side only.
Questions
Does MultiAuth have to be installed on the client?
Which Minecraft version does MultiAuth support?
What happens when two providers use the same player name?
More from azures04
Official listing
- Modrinth page
- modrinth.com/mod/multiauth
- Owner
- azures04
- Published
- 2025-12-30
- Updated on Modrinth
- 2026-01-03
- Facts verified
- 2026-10-15