# flycheck/flycheck

On the fly syntax checking for GNU Emacs

Repository: https://github.com/flycheck/flycheck
Canonical: https://ross.abutalabs.com/products/flycheck
Homepage: https://www.flycheck.org
Language: Emacs Lisp
License: GPL-3.0
License Family: copyleft
Topics: emacs, syntax-checking, flycheck
Last push: 2026-08-26T14:30:34+00:00

## Health v2 (maintenance only)
Score: 98/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 99, release rhythm 97, longevity 100
- inputs: {"age_days": 5075, "days_push": 7, "days_rel": 23, "gap_med": 10, "n_releases_24m": 8}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2534, forks 459 (observed 2026-08-28T04:06:59.112647+00:00)

## What it is
Flycheck is a modern on-the-fly syntax checking extension for GNU Emacs that runs linters and LSP diagnostics as you edit. It supports many bundled language checkers and can display inline diagnostics next to the code.

## Use cases
- show lint errors in emacs while typing
- run syntax checking on save in emacs
- integrate linters like ruff or rubocop into emacs
- display lsp diagnostics inline in emacs buffers
- set up error highlighting for multiple languages in emacs

## When to choose
- you use GNU Emacs and want real-time syntax and lint feedback
- you want a single interface for many language checkers and LSP diagnostics
- you want inline, Error Lens-style diagnostics in your editor

## When to avoid
- you use Vim, Neovim, or VS Code rather than Emacs
- you only need a standalone command-line linter without an editor
- you prefer ALE or built-in LSP diagnostics in another editor

## Facets
- artifact type: plugin
- maturity: active
- function: linter, developer-tools, editor
- domain: developer-tools, text-editors, programming-languages
- platform: editor-plugin, cross-platform
- tags: emacs-lisp, syntax-checking, on-the-fly-linting, lsp-diagnostics, code-quality, emacs

## Member repositories
- flycheck/flycheck (main) score 98

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:59.112647+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 2026-08-30T02:25:15.409120+00:00, confidence not recorded.
  - readme: https://github.com/flycheck/flycheck (fetched 2026-08-28T04:06:59.112647+00:00, sha ac620ae0ca3e)
- Data as of 2026-08-30T08:39:29.467469+00:00.