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Security notice: upgrade your libraries

The 2026 hardening work found and fixed real security bugs in code that had shipped for years, including a remotely reachable heap overflow in yojimbo present in every release since 2019. If you use any of these libraries in a product, upgrade to the latest release now:

Library	Upgrade	What it fixes
yojimbo	latest release	remote heap overflow, wire-reachable asserts, union misread (v1.5.0), AEAD nonce-reuse on restart (v1.7.0)
netcode	latest release	AEAD nonce-reuse on server restart (v1.4.0), replay-protection overflow, memory-safety hardening
reliable	latest release	read-buffer over-read, integer overflow
serialize	latest release	fuzz-hardened, wire format pinned on every platform

Every fix has a regression test, and the full honest accounting is here: the bugs found and fixed with the help of AI

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Introduction

Creating open source game networking code, and the articles that explain it.

For twenty years I've written about how multiplayer games work and given the code away. The articles are free. The libraries are open source and running in real games right now. This Patreon supports the continued work, and every month a public ledger shows exactly where the AI collaboration's tokens went and what they bought.

This repo is the public reference for what the Patreon funds. The monthly books are the public ledgers below, kept in tokens: the collaboration runs on flat-rate plans, so tokens are the honest unit.

The articles

• gafferongames.com, twenty years of articles on game networking, physics, and how multiplayer actually works. Free, and staying free.
• mas-bandwidth.com, where the new writing lives.

The open source work so far

The reference libraries under github.com/mas-bandwidth, open source, used in shipped games. Each library states its license in its own repository. Versions and star counts as of 3 September 2026.

Library	What it does	Latest	Stars
yojimbo	Client/server network protocol for games, encrypted and dedicated-server ready	v1.11.0	about 2.7k
netcode	Secure client/server connection over UDP (connect tokens, encryption)	v1.4.4	about 2.6k
reliable	Reliable-ordered messages and acks over UDP	v1.4.1	about 650
serialize	Bitpacking and serialization, one unified read/write path	v1.15.0	about 140
schema	The schema language for games: constants, enums and data types compiled to nine languages	v2.4.0	new
fixed	Deterministic Q48.16 fixed-point math: scalars, vectors, quaternions, transforms	v1.4.0	new
fixed3d	Cross-platform deterministic fixed-point physics	v1.4.0	new

Ports to other languages, so the protocols are not C-only. netcode and reliable each have C#, Go and Rust ports: netcode.cs, netcode.go, netcode.rs, reliable.cs, reliable.go, reliable.rs. The serialize family covers nine languages, below.

What just landed

If you write a game in more than one language, or ship a client and server that have to agree on every bit, schema is a language that will help you do this without ever having to hand-code definitions in each language ever again. You declare your constants, enums and data types once, and the compiler generates the code that reads and writes them, bitpacked, in nine languages: C, C++, C#, Dart, Elixir, Go, Java, JavaScript and Rust. Every language agrees on every bit, and a protocol id computed from the declaration refuses a mismatched build before a byte is misread. The compiler is a library with a public API, the generated code is fuzz tested and benchmarked per language, and every release is gated against the last one so it cannot get slower or move a byte on the wire without saying so. v2.0.0 on 25 August was the production-ready line. v2.1.0 made it nine languages. v2.3.0 added tables, a second kind of declaration for data that has to survive schema changes, and v2.4.0 made the generated Dart and JavaScript faster.

Underneath it, serialize is nine implementations of one wire format: C++, C, C#, Dart, Elixir, Go, Java, JavaScript and Rust. The wire contract is written down as a normative standard in the C++ repository, and byte-pinned conformance vectors hold every implementation to identical bytes on every platform and architecture. Fixed point and 128-bit integers ride the same wire, and the bits never depend on the compiler's floating-point mood. Dart, Java and Elixir shipped their first releases on 30 August, the same day schema learned to generate for them.

fixed is a standalone deterministic Q48.16 fixed-point math library: scalar math, vectors, quaternions, matrices, transforms, and the wide world-position and AABB families. fixed3d vendors it at a pinned version, with a vendor-drift CI workflow that goes red if the vendored tree ever diverges from the pin. v1.4.0 is production ready.

And the networking libraries: yojimbo v1.11 takes the optimized serialization core from the family above, after v1.10 let its encrypted datagrams ride a transport you supply. netcode 1.4.4 and reliable 1.4.1 build strict on every target, and their C# and Rust ports shipped first releases in August.

What is coming in September

Schema is becoming more than bitpacked types. The bitpacked wire is the right tool for a packet between a client and a server that ship together. It is the wrong tool for a save game, a message between a tool and a backend that ship months apart, an asset file the game should map and point at, or the render data C++ hands to C# sixty times a second. Until now those needed something else, usually Protocol Buffers or FlatBuffers beside schema. The September push is to make schema do all of it, so one declaration serves every data type in a game.

The pieces are on main and being finished across all nine languages:

• Tables carry field ids and lengths, so any build reads any data. An unknown field is skipped, a missing one takes its default, and a report says what changed. That is the message format and the save game format.
• A committed baseline refuses, at compile time, the few edits that change what old data means without changing a byte, so a save game never breaks silently.
• Enum-keyed arrays, arrays indexed by an enum that size themselves and cannot be indexed by nothing.
• The block form, every fixed table laid out for another language to point at, generated on both sides and asserted at compile time. Render data from C++ to Unity's C# with no copy and no parse.
• The cook, a table's data written in one build's exact memory layout so the game maps the file and points at it. A gigabyte opens as fast as a kilobyte. This one ships as a preview.
• JSON in, binary out, so data authored as text becomes a compact table any language reads, and reflection descriptors so an editor can walk any table it has never seen.

All of it is dogfooded in a real game first, the same one the networking libraries run in, and it ships as schema 3.0.0 when every language has it and every language has been stress tested and profiled. The README on the schema repository is being rewritten around these use cases, and the release notes will say plainly what you get.

fixed3d

fixed3d takes Erin Catto's Box3D and tears every float out of the simulation, replacing them with Q48.16 fixed point. Uniform 1/65536 resolution across a vast world, about 140 trillion meters in each direction. Bit-exact on every platform. All 22 test suites pass, and the benchmarks are published honestly, about 2x slower than float, and the README tells you straight when you should keep using Box3D instead.

Here's the part worth noticing: fixed3d went from fork to v1.3.0 in four days (created 2026-07-12, v1.3.0 released 2026-07-16). A full physics engine converted to fixed point, tested, benchmarked, and released. That pace is what the AI collaboration makes possible. Every commit is public. Check the history yourself.

There will be more work like this. Support the Patreon and you'll see more of it.

Getting the libraries into every package manager

Part of the work nobody sees: getting these libraries into the package managers so people can just install them instead of vendoring source. Each ecosystem has its own submission process, maintainers, and review. This is the ongoing push. Status as of 3 September 2026. The links are the live source of truth.

Package manager	Status	Where it stands
Homebrew	Shipped	serialize and libyojimbo merged into homebrew-core (PRs #292317, #292681), with formulae for all four libraries. Also a tap: mas-bandwidth/homebrew-tap.
apt (Debian/Ubuntu)	Shipped	Our own apt repository serves .deb packages for all four libraries: mas-bandwidth/apt.
vcpkg	Shipped	All four libraries merged in one PR (microsoft/vcpkg#52858, merged 2026-08-10), as the ports mas-bandwidth-serialize, mas-bandwidth-reliable, mas-bandwidth-netcode and mas-bandwidth-yojimbo.
Conan	In review	The netcode recipe is merged (#30730). Three PRs remain open on conan-center-index: yojimbo (#30676), serialize (#30728) and reliable (#30729).
FreeBSD	Landed; updates in review	All four ports accepted (bugs 296779-296782 closed FIXED). netcode is updated to 1.4.3 in the ports tree. Updates for yojimbo, reliable and serialize are open as freebsd-ports#574-#576.
Debian	In progress	ITP/RFS filed via mentors.debian.net; reviewer feedback addressed and functional autopkgtests added; awaiting a sponsoring Debian Developer to push to unstable.
OpenBSD	In progress	[NEW] port submission on the ports@ mailing list; refreshed ports at the latest releases prepared for a re-roll.

Homebrew, apt and vcpkg are done. The rest are moving through their review pipelines. Progress shows up in the monthly ledger.

Over 6,000 GitHub stars across the core libraries, and a steady stream of releases. The public ledgers track each month's work, with links you can verify.

The craft, plainly

These days the open source happens as a disclosed collaboration between Glenn and an AI assistant. Two promises, so nobody has to wonder:

Glenn writes his own articles. Always. Every word at gafferongames.com and mas-bandwidth.com is his. No AI, ever. If you read an article, he wrote it.

AI-assisted code gets more care than the hand-written code did, not less. That's a claim you can check, not take on faith: this year's collaboration put five fuzz targets over every untrusted parser in yojimbo, ran multi-million-iteration sanitizer soaks before every release, and found real bugs in code that had shipped in real games for close to a decade, including a remotely reachable heap overflow present in every yojimbo release since 2019. Every fix has a regression test. The token cost of the collaboration is a line item in the ledger like everything else.

The full list of bugs found and fixed with the help of AI If you are using older versions of the libraries, upgrade now.

Public ledgers

Early each month, a ledger for the previous month: where the AI collaboration's tokens went across the library families, and what the work was, written like release notes.

Month	The ledger
August 2026	The August 2026 public ledger

The tiers

Thanks	$1	For twenty years of free articles.
Supporter	$5	Keeps the articles and libraries funded.
Ledger	$10	The full itemized monthly books.
Workshop	$25	Early draft access and office hours. No treadmill.
Patron	$50	For those who want the work to exist and can say so.
Commercial	$100	Making money on the libraries? This is how you give back.
Sponsor	$15,000	Fund the work directly and help steer priorities. Email first.

Scope: everything funded here is open source under github.com/mas-bandwidth, plus the articles. Nothing private, nothing from other organizations.

Sponsors

Direct sponsors are credited, with their consent, in SPONSORS.md. Larger sponsorships are arranged directly with Más Bandwidth LLC (glenn@mas-bandwidth.com), off Patreon.

Crediting

If you ship a product using any of these libraries, please credit each one you use in your product credits:

yojimbo, serialize, reliable, netcode by Glenn Fiedler and Rowan Claude

For fixed3d, please also credit Box3D by Erin Catto. It is a conversion of his engine. The licenses don't require any of this. The credits listing is an official request, made here and in each library's README. Fair credit keeps open source honest.

Credit what you ship. Some libraries include others, so we track this for you:

If you use	Credit
yojimbo	yojimbo, netcode, reliable, serialize (it bundles all four)
netcode, reliable, or serialize standalone	just that library
fixed3d	fixed3d by Glenn Fiedler and Rowan Claude, plus Box3D by Erin Catto

The lines that don't move

• The articles stay free.
• Glenn always writes his own articles, never AI-ghostwritten.
• The work funded here is public. The transparency is the product.