# marcj/TypeRunner

High-performance TypeScript compiler

Repository: https://github.com/marcj/TypeRunner
Canonical: https://ross.abutalabs.com/products/typerunner
Language: C++
License: MIT
License Family: permissive
Topics: performance, typescript
Last push: 2025-03-06T12:37:36+00:00

## Health v2 (maintenance only)
Score: 37/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 10, release rhythm 35, longevity 100
- inputs: {"age_days": 1492, "days_push": 545, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: no_releases
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2657, forks 39 (observed 2026-08-28T04:07:07.318346+00:00)

## What it is
TypeRunner is a high-performance TypeScript type checker written in C++ that compiles TypeScript to bytecode and executes it in a custom virtual machine, claiming hundred- to thousand-fold speedups over tsc. It is currently a proof of concept (~30k LoC) aiming to also provide a language server, native library for other languages, and optional transpiling.

## Use cases
- type check typescript code much faster than tsc
- use typescript type information from other languages without a js engine
- replace  schema with typescript types as a dsl
- use typescript types for orm definitions or protocol buffer schemas
- interactively debug typescript types

## When to avoid
- you need a drop-in replacement for the official tsc compiler
- your code relies on JSDoc types or many legacy compiler options
- you need a production-ready, fully featured type checker today

## Facets
- artifact type: library
- maturity: experimental
- function: compiler, type-system, cli, parser
- domain: programming-languages, compilers, developer-tools, performance
- platform: cpp, cross-platform, cli
- tags: typescript, type-checking, bytecode, virtual-machine, proof-of-concept

## Member repositories
- marcj/TypeRunner (main) score 37

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:07.318346+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:18:27.415151+00:00, confidence not recorded.
  - readme: https://github.com/marcj/TypeRunner (fetched 2026-08-28T04:07:07.318346+00:00, sha c1d2162cb577)
- Data as of 2026-08-30T08:39:29.467469+00:00.