Compatibility
What works with Minecraft 1.21.9
Released 30 Sept 2025. Everything below comes from the projects' own published data, and each row says how we know.
Java requirement
Java 21 or newer
Published by Mojang for this exact version. An older runtime will not start it. Get a verified build.
Server software with builds
Real, downloadable builds for 1.21.9.
| Software | Build | Published | Size | Checksum | Download |
|---|---|---|---|---|---|
| ASPaper | #16800 | 6 Oct 2025 | 57.4 MB | Not published | jar ↗ |
| LooHP Limbo | #62 | 6 Oct 2025 | 7.6 MB | Not published | jar ↗ |
| Paper | #59 | 7 Oct 2025 | 51.0 MB | aec002e77c75… | jar ↗ |
| Pluto | #35 | 13 Apr 2026 | 51.4 MB | Not published | jar ↗ |
| Purpur | #2505 | 7 Oct 2025 | Unknown | Not published | jar ↗ |
| Spigot | #4540 | 7 Oct 2025 | 78.5 MB | Not published | jar ↗ |
| Sponge | #7 | 28 Jul 2026 | 8.2 MB | Not published | jar ↗ |
Mod loaders
Support declared in each loader's own metadata.
- Spigot#4540inferredsupported
- ASPaper#16800inferredsupported
- LooHP Limbo#62inferredsupported
- Sponge1.21.9-17.0.0-RC2374inferredsupported
- Pluto#35inferredsupported
- Minecraft Forge59.0.5declaredsupported
- Fabric Loader0.19.3declaredsupported
- Quilt Loader0.30.1-beta.2declaredsupported
- NeoForge21.9.16-betadeclaredsupported
Clients that can join
Protocol 773 is shared with these versions, so they can connect without a translation proxy.
Frequently asked
Which Java version does Minecraft 1.21.9 need?
Java 21 or newer. Mojang publishes this requirement in the version metadata, so an older runtime will refuse to start the server.
Which Minecraft versions can connect to a 1.21.9 server?
Any client speaking protocol 773: 1.21.10. Versions with a different protocol number need a translation proxy such as ViaVersion.
Which server software supports 1.21.9?
ASPaper, LooHP Limbo, Paper, Pluto, Purpur, Spigot, Sponge publish builds for 1.21.9.