#link-checker #broken #markup #html #markdown

bin+lib mlc

The markup link checker (mlc) checks for broken links in markup files

54 releases

0.16.3 Nov 20, 2023
0.16.2 Jun 15, 2023
0.16.1 Dec 19, 2022
0.15.4 Aug 23, 2022
0.1.1 Jun 7, 2018

#115 in Text processing

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996 downloads per month

MIT license

1.5K SLoC

Markup Link Checker

crates.io downloads build status license PRs welcome


Check for broken links in markup files. Currently html and markdown files are supported. The Markup Link Checker can easily be integrated in your CI pipeline to prevent broken links in your markup docs.


  • Find and check links in markdown and html files
  • Support HTML links and plain URLs in markdown files
  • Validated absolute and relative file paths and URLs
  • User friendly command line interface
  • Easy CI pipeline integration
  • Very fast execution using async
  • Efficient link resolving strategy which tries with minimized network load
  • Throttle option to prevent 429 Too Many Requests errors
  • Configure via config file
  • Report broken links via GitHub workflow commands

Install Locally

There are different ways to install and use mlc.


Use rust's package manager cargo to install mlc from crates.io:

cargo install mlc

Download Binaries

To download a compiled binary version of mlc go to github releases and download the binaries compiled for x86_64-unknown-linux-gnu and x86_64-apple-darwin.

CI Pipeline Integration

GitHub Actions

Use mlc in GitHub using the GitHub-Action from the Marketplace.

- name: Markup Link Checker (mlc)
  uses: becheran/mlc@v0.16.3

Use mlc command line arguments using the with argument:

- name: Markup Link Checker (mlc)
  uses: becheran/mlc@v0.16.3
    args: ./README.md

The action does uses GitHub workflow commands to highlight broken links:



To integrate mlc in your CI pipeline running in a linux x86_64 environment you can add the following commands to download the tool:

curl -L https://github.com/becheran/mlc/releases/download/v0.16.3/mlc-x86_64-linux -o mlc
chmod +x mlc

For example take a look at the ntest repo which uses mlc in the CI pipeline.


Use the mlc docker image from the docker hub which includes mlc.


Once you have mlc installed, it can be called from the command line. The following call will check all links in markup files found in the current folder and all subdirectories:


Another example is to call mlc on a certain directory or file:

mlc ./docs

Call mlc with the --help flag to display all available cli arguments:

mlc -h

The following arguments are available:

Argument Short Description
<directory> Only positional argument. Path to directory which shall be checked with all sub-dirs. Can also be a specific filename which shall be checked.
--help -h Print help
--debug -d Show verbose debug information
--offline -o Do not check any web links. Renamed from --no-web-links which is still an alias for downwards compatibility
--match-file-extension -e Set the flag, if the file extension shall be checked as well. For example the following markup link [link](dir/file) matches if for example a file called file.md exists in dir, but would fail when the --match-file-extension flag is set.
--version -V Print current version of mlc
--ignore-path -p Comma separated list of directories or files which shall be ignored. For example
--ignore-links -i Comma separated list of links which shall be ignored. Use simple ? and * wildcards. For example --ignore-links "http*://crates.io*" will skip all links to the crates.io website. See the used lib for more information.
--markup-types -t Comma separated list list of markup types which shall be checked [possible values: md, html]
--root-dir -r All links to the file system starting with a slash on linux or backslash on windows will use another virtual root dir. For example the link in a file [link](/dir/other/file.md) checked with the cli arg --root-dir /env/another/dir will let mlc check the existence of /env/another/dir/dir/other/file.md.
--throttle -T Number of milliseconds to wait in between web requests to the same host. Default is zero which means no throttling. Set this if you need to slow down the web request frequency to avoid 429 - Too Many Requests responses. For example with --throttle 15, between each http check to the same host, 15 ms will be waited. Note that this setting can slow down the link checker.

All optional arguments which can be passed via the command line can also be configured via the .mlc.toml config file in the working dir where mlc is started:

# Print debug information to console
debug = true
# Do not check web links
offline = true
# Check the exact file extension when searching for a file
match-file-extension= true
# List of files and directories which will be ignored
# List of links which will be ignored
# List of markup types which shall be checked
# Wait time in milliseconds between http request to the same host
throttle= 100
# Path to the root folder used to resolve all relative paths


Checkout the changelog file to see the changes between different versions.


This project is licensed under the MIT License - see the LICENSE file for more details.


~559K SLoC