lychee 0.5.0

A glorious link checker
Documentation

lychee

Rust docs.rs

A fast, async, resource-friendly link checker written in Rust.
For GitHub links, it can optionally use a GITHUB_TOKEN to avoid getting blocked by the rate limiter.

Lychee demo

Features

This comparison is made on a best-effort basis. Please create a PR to fix outdated information. use

lychee awesome_bot muffet broken-link-checker linkinator linkchecker markdown-link-check fink
Language Rust Ruby Go JS TypeScript Python JS PHP
Async/Parallel yes yes yes yes yes yes yes yes
JSON output yes no yes yes yes maybe1 yes yes
Static binary yes no yes no no ️ no no no
Markdown files yes yes no no no yes ️ yes no
HTML files yes no no yes yes no yes no
Text files yes no no no no no no no
Website support yes no yes yes yes yes no yes
Chunked encodings yes maybe maybe maybe maybe no yes yes
GZIP compression yes maybe maybe yes maybe yes maybe no
Basic Auth yes no no yes no yes no no
Custom user agent yes no no yes no yes no no
Relative URLs yes yes no yes yes yes yes yes
Skip relative URLs yes no no maybe no no no no
Include patterns yes️ yes no yes no no no no
Exclude patterns yes no yes yes yes yes yes yes
Handle redirects yes yes yes yes yes yes yes yes
Ignore insecure SSL yes yes yes no no yes no yes
File globbing yes yes no no yes no yes no
Limit scheme yes no no yes no yes no no
Custom headers yes no yes no no no yes yes
Summary yes yes yes maybe yes yes no yes
HEAD requests yes yes no yes yes yes no no
Colored output yes maybe yes maybe yes yes no yes
Filter status code yes yes no no no no yes no
Custom timeout yes yes yes no yes yes no yes
E-mail links yes no no no no yes no no
Progress bar yes yes no no no yes yes yes
Retry and backoff yes no no no yes no yes no
Skip private domains yes no no no no no no no
Use as library yes yes no yes yes no yes no
Quiet mode yes no no no yes yes yes yes
Config file yes no no no yes yes yes no
Recursion no no no yes yes yes yes no
Amazing lychee logo yes no no no no no no no

1 Other machine-readable formats like CSV are supported.

Contributing to lychee

We'd be thankful for any contribution.
We try to keep the issue-tracker up-to-date so you can quickly find a task to work on.

Try one of these links to get started:

Using the Commandline Client

You can run lychee directly from the commandline.

Installation

Using cargo

cargo install lychee

Using the official Docker image

docker pull lycheeverse/lychee

Using pre-built binaries

We provide binaries for Linux, macOS, and Windows for every release.
You can download them from the releases page.

Commandline usage

Run it inside a repository with a README.md:

lychee

You can also specify various types of inputs:

# check links on a website:
lychee https://endler.dev/

# check links in a remote file:
lychee https://raw.githubusercontent.com/lycheeverse/lychee/master/README.md

# check links in local file(s):
lychee README.md
lychee test.html info.txt

# check links in local files (by shell glob):
lychee ~/projects/*/README.md

# check links in local files (lychee supports advanced globbing and ~ expansion):
lychee "~/projects/big_project/**/README.*"
# ignore case when globbing, displaying progress and check result for each link:
lychee --glob-ignore-case --progress --verbose "~/projects/**/[r]eadme.*"

GitHub token

Optionally, to avoid getting rate-limited while checking GitHub links, you can set an environment variable with your Github token like so GITHUB_TOKEN=xxxx, or use the --github-token CLI option. It can also be set in the config file.

The token can be generated in your GitHub account settings page. A personal token with no extra permissions is enough to be able to check public repos links.

Commandline Parameters

There is an extensive list of commandline parameters to customize the behavior, see below for a full list.

USAGE:
    lychee [FLAGS] [OPTIONS] [--] [inputs]...

FLAGS:
    -E, --exclude-all-private    Exclude all private IPs from checking. Equivalent to `--exclude-private --exclude-link-
                                 local --exclude-loopback`
        --exclude-link-local     Exclude link-local IP address range from checking
        --exclude-loopback       Exclude loopback IP address range from checking
        --exclude-private        Exclude private IP address ranges from checking
        --glob-ignore-case       Ignore case when expanding filesystem path glob inputs
        --help                   Prints help information
    -i, --insecure               Proceed for server connections considered insecure (invalid TLS)
    -p, --progress               Show progress
        --skip-missing           Skip missing input files (default is to error if they don't exist)
    -V, --version                Prints version information
    -v, --verbose                Verbose program output

OPTIONS:
    -a, --accept <accept>                      Comma-separated list of accepted status codes for valid links
    -b, --base-url <base-url>                  Base URL to check relative URLs
        --basic-auth <basic-auth>              Basic authentication support. E.g. `username:password`
    -c, --config <config-file>                 Configuration file to use [default: ./lychee.toml]
        --exclude <exclude>...                 Exclude URLs from checking (supports regex)
    -f, --format <format>                      Output file format of status report [default: string]
        --github-token <github-token>          GitHub API token to use when checking github.com links, to avoid rate
                                               limiting [env: GITHUB_TOKEN=]
    -h, --headers <headers>...                 Custom request headers
        --include <include>...                 URLs to check (supports regex). Has preference over all excludes
        --max-concurrency <max-concurrency>    Maximum number of concurrent network requests [default: 128]
    -m, --max-redirects <max-redirects>        Maximum number of allowed redirects [default: 10]
    -X, --method <method>                      Request method [default: get]
    -o, --output <output>                      Output file of status report
    -s, --scheme <scheme>                      Only test links with the given scheme (e.g. https)
    -T, --threads <threads>                    Number of threads to utilize. Defaults to number of cores available to
                                               the system
    -t, --timeout <timeout>                    Website timeout from connect to response finished [default: 20]
    -u, --user-agent <user-agent>              User agent [default: lychee/0.5.0]

ARGS:
    <inputs>...    The inputs (where to get links to check from). These can be: files (e.g. `README.md`), file globs
                   (e.g. `"~/git/*/README.md"`), remote URLs (e.g. `https://example.com/README.md`) or standard
                   input (`-`). Prefix with `--` to separate inputs from options that allow multiple arguments
                   [default: README.md]

Exit codes

  • 0 for success (all links checked successfully or excluded/skipped as configured)
  • 1 for missing inputs and any unexpected runtime failures or config errors
  • 2 for link check failures (if any non-excluded link failed the check)

Library usage

You can use lychee as a library for your own projects. Simply add it as a dependency and build your client:

use http::StatusCode

let client = lychee::ClientBuilder::default().build()?;
let url = Url::parse("https://github.com/lycheeverse/lychee")?;
let response = client.check(Website(url)).await?;
assert!(matches!(response.status, Status::Ok(_)));

The client is very customizable, e.g.

let client = lychee::ClientBuilder::default()
    .includes(includes)
    .excludes(excludes)
    .max_redirects(cfg.max_redirects)
    .user_agent(cfg.user_agent)
    .allow_insecure(cfg.insecure)
    .custom_headers(headers)
    .method(method)
    .timeout(timeout)
    .verbose(cfg.verbose)
    .github_token(cfg.github_token)
    .scheme(cfg.scheme)
    .accepted(accepted)
    .build()?;

See the builder documentation for all options.

Troubleshooting and workarounds

We collect a list of common workarounds for various websites in our troubleshooting guide.

Users

If you are using lychee for your project, we'd be delighted to hear about it.

License

lychee is licensed under either of

at your option.

Credits

The first prototype of lychee was built in episode 10 of Hello Rust. Thanks to all Github- and Patreon sponsors for supporting the development since the beginning. Also, thanks to all the great contributors who have since made this project more mature.