Chiyogami is a free and open-source Minecraft server implementation forked from Paper. It keeps Paper’s Spigot plugin compatibility but changes how the server schedules work: instead of ticking every loaded world on a single thread, Chiyogami gives each world its own thread and synchronises between them optimistically, so a multi-core machine is no longer limited to the throughput of one core.

Key Features

• Paper fork, Spigot-compatible — the fork starts from PaperMC’s Paper, so existing Spigot and Paper plugins are meant to run without modification and an existing world can be moved across
• One thread per world — every loaded world is assigned its own thread and worlds synchronise optimistically instead of through one global tick loop
• Event handling stays guarded by default — event dispatch is serialised by default, but the order of events between worlds is not guaranteed, which the project calls out as a constraint plugin authors must respect
• Several Minecraft version tracks — separate branches and snapshot builds for 1.21.8, 1.21.11, 26.1.2 and 26.2, with the current snapshot series at v0.0.7
• Plugin API for the threading model — the companion ChiyogamiLib exposes world-level threading to plugins
• Built from source with Gradle — JDK 25 is required; run ./gradlew applyAllPatches and then ./gradlew createBundlerJar to produce the server jar
• Runs on any JVM host — the release artifact is a plain Java server jar, so it runs on a self-hosted Linux, Windows or macOS machine or on a small VPS

Status and caveats

The project describes itself as still in a development stage that has not been tested thoroughly, and asks operators to back up world data before running it. Releases are snapshot builds rather than stable versions, and the documentation and issue tracker are mainly in Japanese. Feedback is collected through GitHub issues and the project’s Discord server.

What it is not

Chiyogami is not a Minecraft client or a launcher — it is only the server side, and players still connect with a normal Minecraft Java Edition client. For a separate free voxel game and engine that does not require Minecraft at all, see Luanti.

Licence

Chiyogami is distributed as source on GitHub and does not include a separate licence file. It is a fork of Paper, which is released under the GNU GPL v3, so the inherited GPL-3.0 terms should be treated as governing the fork; confirm with the project before redistributing a modified build.