linkinator

🐿 linkinator

A super simple site crawler and broken link checker.

Behold my latest inator! The linkinator provides an API and CLI for crawling websites and validating links. It's got a ton of sweet features:

• 🔥 Easily perform scans on remote sites or local files
• 🔥 Scan any element that includes links, not just <a href>
• 🔥 Supports redirects, absolute links, relative links, all the things
• 🔥 Configure specific regex patterns to skip
• 🔥 Scan markdown files without transpilation

Installation

npm install linkinator

Not into the whole node.js or npm thing? You can also download a standalone binary that bundles node, linkinator, and anything else you need. See releases.

Command Usage

You can use this as a library, or as a CLI. Let's see the CLI!

$ linkinator LOCATIONS [ --arguments ]

  Positional arguments

    LOCATIONS
      Required. Either the URLs or the paths on disk to check for broken links.
      Supports multiple paths, and globs.

  Flags

    --concurrency
          The number of connections to make simultaneously. Defaults to 100.

    --config
        Path to the config file to use. Looks for `linkinator.config.json` by default.

    --directory-listing
        Include an automatic directory index file when linking to a directory.
        Defaults to 'false'.

    --format, -f
        Return the data in CSV or JSON format.

    --help
        Show this command.

    --include, -i
        List of urls in regexy form to include.  The opposite of --skip.

    --markdown
        Automatically parse and scan markdown if scanning from a location on disk.

    --recurse, -r
        Recursively follow links on the same root domain.

    --retry,
        Automatically retry requests that return HTTP 429 responses and include
        a 'retry-after' header. Defaults to false.

    --retry-errors,
        Automatically retry requests that return 5xx or unknown response.

    --retry-errors-count,
        How many times should an error be retried?

    --retry-errors-jitter,
        Random jitter applied to error retry.

    --server-root
        When scanning a locally directory, customize the location on disk
        where the server is started.  Defaults to the path passed in [LOCATION].

    --skip, -s
        List of urls in regexy form to not include in the check.

    --timeout
        Request timeout in ms.  Defaults to 0 (no timeout).

    --url-rewrite-search
        Pattern to search for in urls.  Must be used with --url-rewrite-replace.

    --url-rewrite-replace
        Expression used to replace search content.  Must be used with --url-rewrite-search.

    --user-agent
        The user agent passed in all HTTP requests. Defaults to 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.117 Safari/537.36'

    --verbosity
        Override the default verbosity for this command. Available options are
        'debug', 'info', 'warning', 'error', and 'none'.  Defaults to 'warning'.

Command Examples

You can run a shallow scan of a website for busted links:

npx linkinator https://jbeckwith.com

That was fun. What about local files? The linkinator will stand up a static web server for yinz:

npx linkinator ./docs

But that only gets the top level of links. Lets go deeper and do a full recursive scan!

npx linkinator ./docs --recurse

Aw, snap. I didn't want that to check those links. Let's skip em:

npx linkinator ./docs --skip www.googleapis.com

The --skip parameter will accept any regex! You can do more complex matching, or even tell it to only scan links with a given domain:

npx linkinator http://jbeckwith.com --skip '^(?!http://jbeckwith.com)'

Maybe you're going to pipe the output to another program. Use the --format option to get JSON or CSV!

npx linkinator ./docs --format CSV

Let's make sure the README.md in our repo doesn't have any busted links:

npx linkinator ./README.md --markdown

You know what, we better check all of the markdown files!

npx linkinator "**/*.md" --markdown

Configuration file

You can pass options directly to the linkinator CLI, or you can define a config file. By default, linkinator will look for a linkinator.config.json file in the current working directory.

All options are optional. It should look like this:

{
  "concurrency": 100,
  "config": "string",
  "recurse": true,
  "skip": "www.googleapis.com",
  "format": "json",
  "silent": true,
  "verbosity": "error",
  "timeout": 0,
  "markdown": true,
  "serverRoot": "./",
  "directoryListing": true,
  "retry": true,
  "retryErrors": true,
  "retryErrorsCount": 3,
  "retryErrorsJitter": 5,
  "urlRewriteSearch": "/pattern/",
  "urlRewriteReplace": "replacement",
  "userAgent": "Mozilla/4.0 (compatible; MSIE 6.0; MSIE 5.5; Windows NT 5.1)",
}

To load config settings outside the CWD, you can pass the --config flag to the linkinator CLI:

npx linkinator --config /some/path/your-config.json

GitHub Actions

You can use linkinator as a GitHub Action as well, using JustinBeckwith/linkinator-action:

on:
  push:
    branches:
      - main
  pull_request:
name: ci
jobs:
  linkinator:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: JustinBeckwith/linkinator-action@v1
        with:
          paths: README.md

To see all options or to learn more, visit JustinBeckwith/linkinator-action.

API Usage

linkinator.check(options)

Asynchronous method that runs a site wide scan. Options come in the form of an object that includes:

• path (string|string[]) - A fully qualified path to the url to be scanned, or the path(s) to the directory on disk that contains files to be scanned. required.
• concurrency (number) - The number of connections to make simultaneously. Defaults to 100.
• port (number) - When the path is provided as a local path on disk, the port on which to start the temporary web server. Defaults to a random high range order port.
• recurse (boolean) - By default, all scans are shallow. Only the top level links on the requested page will be scanned. By setting recurse to true, the crawler will follow all links on the page, and continue scanning links on the same domain for as long as it can go. Results are cached, so no worries about loops.
• retry (boolean|RetryConfig) - Automatically retry requests that respond with an HTTP 429, and include a retry-after header. The RetryConfig option is a placeholder for fine-grained controls to be implemented at a later time, and is only included here to signal forward-compatibility.
• serverRoot (string) - When scanning a locally directory, customize the location on disk where the server is started. Defaults to the path passed in path.
• timeout (number) - By default, requests made by linkinator do not time out (or follow the settings of the OS). This option (in milliseconds) will fail requests after the configured amount of time.
• markdown (boolean) - Automatically parse and scan markdown if scanning from a location on disk.
• linksToSkip (array | function) - An array of regular expression strings that should be skipped, OR an async function that's called for each link with the link URL as its only argument. Return a Promise that resolves to true to skip the link or false to check it.
• directoryListing (boolean) - Automatically serve a static file listing page when serving a directory. Defaults to false.
• urlRewriteExpressions (array) - Collection of objects that contain a search pattern, and replacement.
• userAgent (string) - The user agent that should be passed with each request. This uses a reasonable default.

linkinator.LinkChecker()

Constructor method that can be used to create a new LinkChecker instance. This is particularly useful if you want to receive events as the crawler crawls. Exposes the following events:

• pagestart (string) - Provides the url that the crawler has just started to scan.
• link (object) - Provides an object with
  • url (string) - The url that was scanned
  • state (string) - The result of the scan. Potential values include BROKEN, OK, or SKIPPED.
  • status (number) - The HTTP status code of the request.

Examples

Simple example

import { LinkChecker } from 'linkinator';

async function simple() {
  const checker = new LinkChecker();
  const results = await checker.check({
    path: 'http://example.com'
  });

  // To see if all the links passed, you can check `passed`
  console.log(`Passed: ${results.passed}`);

  // Show the list of scanned links and their results
  console.log(results);

  // Example output:
  // {
  //   passed: true,
  //   links: [
  //     {
  //       url: 'http://example.com',
  //       status: 200,
  //       state: 'OK'
  //     },
  //     {
  //       url: 'http://www.iana.org/domains/example',
  //       status: 200,
  //       state: 'OK'
  //     }
  //   ]
  // }
}
simple();

Complete example

In most cases you're going to want to respond to events, as running the check command can kinda take a long time.

import { LinkChecker } from 'linkinator';

async function complex() {
  // create a new `LinkChecker` that we'll use to run the scan.
  const checker = new LinkChecker();

  // Respond to the beginning of a new page being scanned
  checker.on('pagestart', url => {
    console.log(`Scanning ${url}`);
  });

  // After a page is scanned, check out the results!
  checker.on('link', result => {

    // check the specific url that was scanned
    console.log(`  ${result.url}`);

    // How did the scan go?  Potential states are `BROKEN`, `OK`, and `SKIPPED`
    console.log(`  ${result.state}`);

    // What was the status code of the response?
    console.log(`  ${result.status}`);

    // What page linked here?
    console.log(`  ${result.parent}`);
  });

  // Go ahead and start the scan! As events occur, we will see them above.
  const result = await checker.check({
    path: 'http://example.com',
    // port: 8673,
    // recurse: true,
    // linksToSkip: [
    //   'https://jbeckwith.com/some/link',
    //   'http://example.com'
    // ]
  });

  // Check to see if the scan passed!
  console.log(result.passed ? 'PASSED :D' : 'FAILED :(');

  // How many links did we scan?
  console.log(`Scanned total of ${result.links.length} links!`);

  // The final result will contain the list of checked links, and the pass/fail
  const brokeLinksCount = result.links.filter(x => x.state === 'BROKEN');
  console.log(`Detected ${brokeLinksCount.length} broken links.`);
}

complex();

Tips & Tricks

Using a proxy

This library supports proxies via the HTTP_PROXY and HTTPS_PROXY environment variables. This guide provides a nice overview of how to format and set these variables.

Globbing

You may have noticed in the example, when using a glob the pattern is encapsulated in quotes:

npx linkinator "**/*.md" --markdown

Without the quotes, some shells will attempt to expand the glob paths on their own. Various shells (bash, zsh) have different, somewhat unpredictable behaviors when left to their own devices. Using the quotes ensures consistent, predictable behavior by letting the library expand the pattern.

Debugging

Oftentimes when a link fails, it's an easy to spot typo, or a clear 404. Other times ... you may need more details on exactly what went wrong. To see a full call stack for the HTTP request failure, use --verbosity DEBUG:

npx linkinator https://jbeckwith.com --verbosity DEBUG

Controlling Output

The --verbosity flag offers preset options for controlling the output, but you may want more control. Using jq and --format JSON - you can do just that!

npx linkinator https://jbeckwith.com --verbosity DEBUG --format JSON | jq '.links | .[] | select(.state | contains("BROKEN"))'

License

MIT