Configuration

seolint loads a config file from the working directory. It looks for these names, in this order:

seolint.config.ts
seolint.config.mjs
seolint.config.cjs
seolint.config.js

import * as config from "seolint/config";

export default config.define({
  host: "https://example.com",
  inputs: ["public"],
  ignore: ["drafts/**"],
  rules: {
    "html.favicon": false,
    "title.content.length": { max: 70 },
    "link.external.limit": ["warn", { max: 10 }],
    "og.*": "error",
  },
});

define() returns the config as it is, but it type-checks it. An unknown rule name, or a wrong option type, is a type error. Command-line options, such as --host, override the same fields.

Fields

Field	Description
`host`	The site URL, such as `https://example.com`.
`inputs`	Files, folders, or URLs to lint, when the command line gives none.
`ignore`	Pages to skip, as glob patterns.
`rules`	Rule settings, by rule name or pattern.
`presets`	Other configs to merge in first.
`plugins`	Your own plugins.
`workers`	How many threads lint pages.

`host`

The URL of your site. seolint uses it to tell internal links from external ones, and to give each page its URL, such as https://example.com/about/ for public/about/index.html.

Without a host, only relative links count as internal, and the rules that compare against the page URL do not run, such as canonical.href.self.

`inputs`

Files, folders, or URLs to lint, relative to the working directory. They must be all paths, or all URLs. See Inputs.

`ignore`

Pages to skip, as glob patterns. Ignored pages are also left out of the site checks, such as unique titles and the sitemap.

In a folder, seolint always skips the error pages: the files with a 4xx or 5xx status code as their name, such as 404.html or fr/500.html. An error page is not for search results. To lint one, give it as a file input, such as seolint public/404.html.

A pattern matches the page's path inside the linted folder, such as blog/draft/index.html. For URLs, it matches the URL path, such as blog/draft/.
* matches within one folder, ** matches across folders, and ? matches one character.
A pattern without / matches at any depth, so print.html also matches fr/print.html.

ignore: ["print.html", "drafts/**", "tags/*/index.html"],

`rules`

Each rule has a default severity, and some rules have options. A setting changes one rule, or every rule that a pattern matches:

Setting	Effect
`false`	Turns the rule off.
`true`	Turns the rule on, with its default severity and options.
`"error"` or `"warn"`	Turns the rule on, with that severity.
`{ ... }`	Turns the rule on, and overrides some of its options.
`["warn", { ... }]`	Sets the severity and some options.

Severity: an error makes the CLI exit with 1. A warn is reported, but it does not change the exit code.
Patterns: a name with *, such as "og.*", sets every rule that matches. Patterns apply first, then exact names, so { "og.*": false, "og.title": true } keeps only og.title.
Unknown names are an error, so a typo does not go unnoticed.

See the rules reference for every rule, its default, and its options.

`presets`

A preset is a config that your config merges in first. seolint has three: strict, essentials, and staging.

import * as config from "seolint/config";
import * as presets from "seolint/presets";

export default config.define({
  presets: [presets.strict],
  rules: { "og.*": false },
});

Your config's own settings apply after its presets. See Presets for how presets merge, and how to write and share your own.

`plugins`

Your own plugins, which run after the built-in ones. See Plugins.

`workers`

seolint lints large sites in worker threads. By default, it uses one worker for about every 8 MB of HTML, up to half the CPU cores. Smaller sites, and URLs, stay on one thread, because a worker takes about 0.1 seconds to start.

workers: 4, // four threads
workers: 1, // one thread

The --workers option overrides it for one run, such as seolint --workers 1.

Each worker loads your plugins from the config file again. Plugins that you pass straight to the API stay on one thread, and workers above 1 is then an error.