MultiLogin Compat Mod
by wifi-left
MultiLogin Compat Mod is a Fabric server-side mod that hands each player's login to a configured MC-MultiLogin-service endpoint, and it is meant to be paired with that service.
What it does
On join, the mod calls the apiUrl set in its config file, which points to the base URL of the MC-MultiLogin-service method it should use. The service decides whether the login succeeds, and the mod forwards the reason it returns, such as DUPLICATE NAME, BANNED or FOUND, so the player sees a specific message instead of a generic failure. The login method is the only part the mod changes; it reports login-failed messages and leaves the rest of the server alone.
Setup means placing the JAR in the server's mods directory, starting the server once so a default config file is generated, editing apiUrl, and restarting the server. Because the mod runs on the server alone, players join without installing anything. The build is written to build/libs/ when compiled from source. The project suggests using it with Authlib-Injector, which is the API layer MC-MultiLogin-service provides.
Key features
Service-driven login
Each login request is sent to the MC-MultiLogin-service endpoint named in the config file, and the result decides whether the player may enter.
Detailed failure reasons
Reasons such as DUPLICATE NAME, BANNED and FOUND are passed through to the player as they come from the service.
Configurable auto-rename
When a name is already in use, the mod can rename the player automatically, and the behavior is set in the config.
Generated default config
A default config file appears on first start, so the apiUrl and related options can be edited before the server runs with the mod.
Compatibility
Latest build for each game version and loader.
26.x2 of 2 versions with builds
1.21.x12 of 12 versions with builds
1.20.x7 of 7 versions with builds
1.19.x5 of 5 versions with builds
1.18.x3 of 3 versions with builds
1.17.x2 of 2 versions with builds
1.16.x6 of 6 versions with builds
Only full game releases are shown. This mod publishes no snapshot builds.
How it compares
Auto Server login is a client-side only Fabric mod for 26.1.2 under All rights reserved, so it runs on players' clients rather than on the server. Datapack Injector works on Fabric and Quilt for 1.21.4 – 26.3, and either side can run it without it being required. MultiYggdrasil is a server-side only mod on Fabric, Forge and NeoForge for 1.14 – 26.2 and is open source under the GNU Affero General Public License v3.0 or later, which this mod is not.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| MultiLogin Compat Mod | Fabric | 1.16 – 26.1.1 | Server-side only | 2026-04-01 |
| Auto Server login | Fabric | 26.1.2 | Client-side only | 2026-05-17 |
| Datapack Injector | Fabric and Quilt | 1.21.4 – 26.3 | Client or server, optional | 2026-09-15 |
| MultiYggdrasil | Fabric, Forge and NeoForge | 1.14 – 26.2 | Server-side only | 2026-07-27 |
Questions
Does the compat mod need to be installed on player clients?
What does the server owner need to set before starting?
Which versions does the mod support?
In the catalog
MultiLogin Compat Mod is one of 8,016 Management mods on ModsFinder, and one of 5,930 Management mods for Fabric. 11,522 mods support Minecraft 26.1.1.
More from wifi-left
Similar mods
What the author says
A Fabric server-side mod for Minecraft 1.21.1 (Mojang mappings) that integrates with MC-MultiLogin-service. 一个用于 Minecraft 1.21.1（Mojang 映射表）的 Fabric 服务端模组，用于与 MC-MultiLogin-service 集成，可以实现多源登录方式。
Official listing
- Modrinth page
- modrinth.com/mod/multilogin-compat-mod
- Owner
- wifi-left
- Published
- 2026-03-26
- Updated on Modrinth
- 2026-04-01
- Facts verified
- 2026-10-15