# astral-sh/ty

An extremely fast Python type checker and language server, written in Rust.

Repository: https://github.com/astral-sh/ty
Canonical: https://ross.abutalabs.com/products/ty
Homepage: https://docs.astral.sh/ty/
Language: Python
License: MIT
License Family: permissive
Last push: 2026-08-26T22:11:40+00:00

## Health v2 (maintenance only)
Score: 82/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 87, longevity 34
- inputs: {"age_days": 488, "days_push": 7, "days_rel": 7, "gap_med": 3, "n_releases_24m": 74}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 19562, forks 327 (observed 2026-08-28T04:11:28.859786+00:00)

## What it is
ty is an extremely fast Python type checker and language server written in Rust, backed by Astral (creators of Ruff and uv). It provides rich diagnostics, incremental analysis, and full LSP features like code navigation, completions, and auto-import.

## Use cases
- type check a python project
- faster alternative to mypy
- faster alternative to pyright
- add a python language server to my editor
- get type errors in vscode as i type
- check types in a partially typed codebase
- run type checking in ci

## When to choose
- you need very fast type checking on large Python codebases
- you want an integrated language server with navigation, completions, and inlay hints
- your codebase is only partially typed and you need gradual adoption
- you want configurable rules, per-file overrides, and suppression comments

## When to avoid
- you need a fully mature checker with complete feature coverage - ty is in beta and some type-system features are marked @Todo
- your team is standardized on mypy or Pyright plugins and workflows
- you rely on type-checker features ty does not yet implement

## Facets
- artifact type: cli-tool
- maturity: active
- function: type-system, linter, editor, cli, developer-tools
- domain: developer-tools, programming-languages, testing
- platform: python, rust, cli, cross-platform, editor-plugin
- tags: type-checker, language-server, lsp, static-analysis, python-typing, mypy-alternative, pyright-alternative, astral, command-line, web

## Member repositories
- astral-sh/ty (main) score 82

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:11:28.859786+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 2026-08-29T16:59:57.224981+00:00, confidence not recorded.
  - readme: https://github.com/astral-sh/ty (fetched 2026-08-28T04:11:28.859786+00:00, sha 2da75cf749b8)
  - homepage: https://docs.astral.sh/ty/ (fetched 2026-08-29T07:58:27.313055+00:00, sha b537b61d85c4)
  - site_page: https://docs.astral.sh/ty/installation (fetched 2026-08-29T07:58:27.315668+00:00, sha 74dbd65713ac)
  - site_page: https://docs.astral.sh/ty/features/type-system (fetched 2026-08-29T07:58:27.317654+00:00, sha c0f46f614a58)
  - site_page: https://docs.astral.sh/ty/features/diagnostics (fetched 2026-08-29T07:58:27.319605+00:00, sha 2a71832b4354)
  - site_page: https://docs.astral.sh/ty/features/language-server (fetched 2026-08-29T07:58:27.321284+00:00, sha b73312dcf9b0)
  - site_page: https://docs.astral.sh/ty/reference/typing-faq (fetched 2026-08-29T07:58:27.323589+00:00, sha 780278e5d1fd)
- Data as of 2026-08-30T08:39:29.467469+00:00.