Texcraft

Texcraft is an experimental project to create a composable, LLVM-style framework for building TeX and other typesetting software.

Existing TeX engines (Knuth's original TeX '82, pdfTeX, XeTeX, etc.) all have monolithic software architectures that are not amenable to modification or code sharing. The goal of Texcraft is change this by essentially doing for TeX engines what LLVM did for compilers. In Texcraft, a TeX engine is implemented as a loose collection of libraries that compose together using well-defined APIs. The same code can be shared between engines - for example, Texcraft's implementation of the \count primitive can be used both for TeX '82 (which has 256 memory registers) and pdfTeX (which has over 32,000 registers).

As of 2025, the project is divided into two main sub-projects:

• Texlang is a framework for building fast and correct TeX language interpreters. It provides APIs for defining TeX primitives and is thus the core of any "TeX engine" built with Texcraft. Texlang's standard library contains implementations of many TeX primitives like \count, \def and \expandafter.

• Boxworks is an implementation of the typesetting engine inside TeX. It is designed to be fully independent of the TeX language. One of the main goals of Boxworks is to support creating new non-TeX typesetting languages that use the engine for typesetting.

There are other smaller parts of the project, for example a Rust crates for working with TeX font metric data and DVI output files.

The project manifesto describes the big-picture ideas and goals behind project.

Trying it out

The Texcraft playground is built with Texcraft and can be used to run TeX scripts in the browser.

Locally, with the Git repo checked out, the Texcraft binary can also be used to run TeX scripts; e.g.,

cargo run --bin texcraft run performance/benches/digits_of_pi.tex

The Texcraft binary also has a REPL for writing TeX interactively:

cargo run --bin texcraft repl

These all work with the limited subset of TeX commands that have been implemented. Run cargo run --bin texcraft doc for a list of available commands.

Note the main point of Texcraft is not to produce specific binaries, but rather to be a library for building TeX software. The documentation website has more information.

Getting involved

There is a lot of low hanging fruit that is intentionally left unpicked so people who want to contribute to Texcraft have a good starting point.

Related projects

TeX

• XymosTeX: ongoing project to implement TeX82 in Rust that has made significant progress in many areas, including input and output formats.

• New Typesetting System: fully functional implementation of TeX82, written in Java and completed in 2001. This project turned out be to non-viable for some reasons like performance, but the source code is an excellent reference for those who are writing their own TeX implementations.

• KeenType: a modernized version of the New Typesetting System than can be used for typesetting math formulae.

Non-TeX Typesetting

There are number of active projects that are building typesetters based on non-TeX languages. The TeX language itself is very complex and certain features like incremental compilation are hard or impossible to implement.

• Typst

• Sile

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

There is more information about our licensing on the documentation site.