Schema. The data language for games.
Schema is a data language where you define your constants, enums, flags, types and tables for your game.
From this one definition, schema generates code in multiple languages: C, C++, C#, Dart, Elixir, Go, Java, JavaScript and Rust.
Schema is currently under active development. See ROADMAP.md for details.
If this work helps you, please support it.
Schema is designed to support the following use-cases in game development:
- Packets sent between a client and server.
- Messages sent between your server and backend.
- Save game files that must load in a future game build.
- Game assets cooked to an efficient runtime binary format.
- Render data written in one language and read in another - sixty times per-second.
package example
const MaxHealth = 1000
enum ShipType { Fighter, Corvette, Bomber }
flags ShipFlags { Firing, Thrusting, Disabled }
type Vec3
{
x float64
y float64
z float64
}
type Quaternion
{
x float64
y float64
z float64
w float64 = 1.0
}
type ShipState
{
ship_type ShipType
ship_flags ShipFlags
position Vec3
rotation Quaternion
health int32 | min = 0, max = MaxHealth
at_rest bool
if !at_rest
{
linear_velocity Vec3
angular_velocity Vec3
}
}
Write your data types once and generate bit-packed serialization code to read and write them. Best for client/server messages and state where the client speaks the same binary protocol as the server or won't be allowed to connect.
Cost to serialize a representative game packet, relative to generated C++ at 100%. Lower is faster.
| Language | % |
|---|---|
| C | 100% |
| C++ | 100% |
| Rust | 166% |
| Java | 170% |
| Go | 228% |
| C# | 238% |
| Dart | 266% |
| JavaScript | 288% |
| Elixir | 1479% |
Measured by the benchmark on an Apple M3 Ultra, 2026-09-07, the runtimes at their release tags; PERFORMANCE.md has every toolchain, the earlier Apple M2 table and what moved between them. One 438-byte packet exercising every construct.
make # builds the compiler at bin/schema
bin/schema check <dir of .schema files>
bin/schema generate --lang c|cpp|cs|dart|elixir|go|java|js|rust --out <outdir> <dir>
bin/schema fmt <dir of .schema files>
fmt is the only command that writes a .schema file. Every other command
reads your schema files and leaves them alone, so a read-only checkout, a
sandboxed build and an editor integration all work.
| Document | What's in it |
|---|---|
| ROADMAP.md | Where schema stands, feature by feature and language by language, what we are building next, and how to support the work. |
| TUTORIAL.md | Fourteen parts, from an empty directory to a program that uses every feature. Start here. |
| USAGE.md | Every language feature, with the code it generates. |
| SPEC.md | The normative reference for the type wire: grammar, wire law, every edge case. |
| SPEC-TABLES.md | The normative reference for tables: the wire, the cook, the block form, reflection, the build version. |
Beside them: PORTING.md (the techniques register: every method and instrument a table backend carries, with a cell per language and a gate), PERFORMANCE.md, COMPARISON-TABLES.md (tables against FlatBuffers and Protobuf, feature by feature, with the verdict on every gap), COMPARISON.md (the same packet against Cap'n Proto, Protobuf and FlatBuffers), COMPETITION.md (the standing comparison against Protocol Buffers, FlatBuffers, Cap'n Proto and Avro), FAQ.md, VERSIONING.md, CONTRIBUTING.md and SECURITY.md.
The compiler is AGPL-3.0. The code it generates is yours.
The compiler is licensed under the GNU Affero General Public License v3.0, with an explicit additional permission for generated output written into LICENSE itself and carried in every generated file's own header. The output the compiler produces from your schema files belongs to you, under whatever terms you choose, including in closed-source projects. That grant is intentional and permanent. If you modify the compiler and run it as a service or distribute it, the AGPL's terms apply to those modifications.
Contributing is a separate matter. Contributions are made under a Contributor Assignment Agreement, described in CONTRIBUTING.md.
Glenn Fiedler, Rowan Claude and Stella Codex, Más Bandwidth LLC.