mojo-json

A from-scratch JSON implementation for Mojo. The runtime and the code generator are written in Mojo. They do not wrap, link, or vendor simdjson, yyjson, or any other C, C++, or Rust JSON library.

Python json is a test oracle for golden text. It is not required to encode or decode at runtime.

This repository is a standalone library. It is not part of any other project.

Documentation: leo-gan.github.io/gld-json. That site has a JSON format overview for new readers, the install steps, JSON Schema walkthrough, examples, encode/decode techniques, and test-data notes.

Published package (linux-64) on prefix.dev/leo-gan/leo-gan:

pixi add --channel https://prefix.dev/leo-gan/leo-gan mojo-json

git clone https://github.com/leo-gan/gld-json.git
cd gld-json
pixi install
pixi run test

If pixi install fails with 401 on conda.modular.com, set PREFIX_API_KEY in a local .env (never commit that file) and run scripts/ci-setup.sh.

MIT. Copyright (c) 2026 Leonid Ganeline.