Krypton (NeoForge)

Krypton for NeoForge is a port of the original Krypton by Andrew Steinborn (astei) to NeoForge for Minecraft 26.3. It optimizes the Minecraft networking stack. Most of the benefit is "hidden" — it shows up as lower CPU usage and shorter tick times on busy servers — but it works on the client too. The other side does not need the mod: a modded client can join a vanilla server and vice versa.

Features

Derived from the work of the Velocity and Tuinity projects, exactly like the original mod:

• Native packet compression — replaces java.util.zip with velocity-native (libdeflate on Linux/macOS, a fast pure-Java fallback on Windows), embedded via Jar-in-Jar. No extra downloads.
• Native encryption — swaps the javax.crypto handlers for the Velocity/OpenSSL cipher where available.
• Optimized VarInt frame decoder — branch-light frame splitting from Velocity 1.1.0 with fewer bounds checks, plus a fix against "nullping" attacks.
• Zero-copy frame prepender — the packet length is written to a small separate buffer and the packet body is never copied; the handler is shareable across all connections.
• Serialization micro-optimizations — faster VarInt reads/writes, UTF-8 string encoding without intermediate copies, and a small entity-tracker optimization.
• Netty tuning — pooled allocator arenas reduced from 16 MiB to 4 MiB (Minecraft packets are capped at 2 MiB), and io.netty.leakDetection.level is honored if you set it.

Requirements

• Minecraft: Java Edition 26.3
• Loader: NeoForge 26.3.0.100+
• Java: 25 or newer

Compatibility

Krypton only touches low-level networking and is compatible with almost everything.

• ❌ Do not combine with other Krypton ports/forks: Krypton Reforged, Pluto, KryptonFoxified, Krypton Reno, or the original Fabric Krypton (via connector).
• ⚠️ Anything that heavily rewrites the networking stack may conflict, though these patches are deliberately minimal.

FAQ

Q: Do I need this on both client and server? No. Install it on either side or both — it works one-sided. You get the most benefit by installing it on the server.

Q: Will it lower my ping? It reduces CPU work per packet, which helps when lag comes from an overloaded machine. It cannot beat physics: if your network itself is slow, your ping will not change.

Q: Why does the log say "Compression will use Java, encryption will use Java"? velocity-native ships natives for Linux and macOS only. On Windows it uses its optimized pure-Java fallback — same behavior as the original mod.

Q: Is this an official release by astei? No. This is an unofficial port. Please report issues here, not to the original Krypton issue tracker.

Credits

• Andrew Steinborn (astei) — author of the original Krypton (LGPL-3.0) and the Velocity proxy this work derives from
• PaperMC — velocity-native compression/encryption library
• Port to NeoForge 26.3 by Shark

License

LGPL-3.0, same as the original Krypton. Source code is included; contributions are welcome.

https://github.com/Sharkman96/Krypton-NeoForge