1. Documentation is useful; documentation with broken relative links is less so.
2. mkdocs build --strict is too strict, can not check files outside of docs/ directory.
3. Other existing tools I found were too slow, taking up to 10 seconds. This tool typically runs in milliseconds:

$ hyperfine "relcheck all"
Benchmark 1: relcheck all
  Time (mean ± σ):       7.2 ms ±   0.5 ms    [User: 3.8 ms, System: 3.2 ms]
  Range (min … max):     6.5 ms …   9.7 ms    286 runs

brew install anttiharju/tap/relcheck

Or download a binary from a GitHub release. Update with:

brew update && brew upgrade relcheck

Available via anttiharju/nur-packages. Star the repo so I can release it on nixpkgs!

Using defaults inside a Git repository

relcheck all

for advanced usage, refer to the printed out info from

relcheck

Although the recommendation is to setup a integration via Lefthook or GitHub Actions instead of manual use.

name: Build
on:
  push:
    branches:
      - main
  pull_request:

jobs:
  validate:
    name: Validate
    runs-on: ubuntu-24.04
    steps:
      - name: Checkout
        uses: actions/checkout@v6

      - name: relcheck
        uses: anttiharju/[email protected]

The reported broken links such as dist/brew/README.md:5:19 are clickable in the intergrated terminal when holding ctrl/cmd. It will bring you right to where the ^ indicator points:

$ relcheck all
dist/brew/README.md:5:19: broken relative link (file not found):
- [`values.bash`](./values.sh) is required by the [render-template](https://github.com/anttiharju/actions/tree/v1/render-template) action.
                  ^

The file:line:column link syntax is the same one that golangci-lint uses.

Lefthook is an awesome Git hooks manager, enabling shift-left testing that improves developer experience. relcheck was built for usage with Lefthook. Here is a minimal lefthook.yml example:

output:
  - success
  - failure

pre-commit:
  parallel: true
  jobs:
    # Install from https://github.com/anttiharju/relcheck
    - name: relcheck
      run: relcheck all

This tool was developed alongside and mainly for https://github.com/anttiharju/vmatch. Idea is to have vmatch to be as linted as possible to make maintaining the project a breeze. Additionally the tooling built to support it will make my future projects easier to work on, allowing me to mostly focus on functionality without existing things breaking while I refactor the projects to my will.