6.2.0 • Public • Published

Spellchecker CLI

A command-line tool for spellchecking files, built on top of retext and remark.

Build Status npm downloads pre-commit

Use Case

You can help contributors to your open-source software project catch spelling mistakes in documentation by running Spellchecker CLI as a pre-commit or pre-push Git hook or as part of your continuous integration process.


  • Run on any plain text file, with special handling for Markdown syntax
  • Check for spelling mistakes, repeated words, and/or correct usage of "a" and "and"
  • Check spelling using an American, British, Canadian, Australian, or South African English dictionary
  • Specify a custom dictionary of project-specific terms to be combined with the dictionary for the specified language
  • Generate the custom dictionary automatically based on misspellings found in the checked files


If you want to use Spellchecker CLI in a GitHub Actions workflow, try:

If you want to use Spellchecker CLI as a command-line tool on your own computer, you can install it globally:

npm install --global spellchecker-cli

# or

yarn global add spellchecker-cli

If you want to run Spellchecker CLI in a Git hook or in a CI environment, it's better to add it as a development dependency of your application:

npm install --save-dev spellchecker-cli

# or

yarn add --dev spellchecker-cli

If you want to use the Spellchecker CLI as part of a pre-commit hook:

- repo: https://github.com/tbroadley/spellchecker-cli
    - id: spellchecker-cli
      name: spellcheck
      types: [markdown]
      stages: # optional: if you want to specify stages to run the hook on
        - '' # see https://pre-commit.com/#confining-hooks-to-run-at-certain-stages


Run Spellchecker CLI using the command spellchecker. This command takes the following options:

-f, --files <file|glob> <file|glob>...   A list of files or globs to spellcheck.
-l, --language <language>                The language of the files. The default language is en-US. The following
                                         languages are supported: en-AU, en-CA, en-GB, en-US, en-ZA, vi.
-d, --dictionaries <file> <file>...      Files to combine into a personal dictionary.
--generate-dictionary <file>             Write a personal dictionary that contains all found misspellings. Optionally,
                                         provide a filepath for the dictionary. The default filepath is
--no-gitignore                           Don't respect ignore files (.gitignore, .ignore, etc.).
-i, --ignore <regex> <regex>...          Spelling mistakes that match any of these regexes (after being wrapped with ^
                                         and $) will be ignored.
-p, --plugins <name> <name>...           A list of retext plugins to use. The default is "spell indefinite-article
                                         repeated-words syntax-mentions syntax-urls". The following plugins are
                                         supported: spell, indefinite-article, repeated-words, syntax-mentions,
                                         syntax-urls, frontmatter.
--no-suggestions                         Do not print suggested replacements for misspelled words. This option will
                                         improve Spellchecker's runtime when many errors are detected.
-q, --quiet                              Do not output anything for files that contain no spelling mistakes.
--frontmatter-keys <key> <key>...        A list of frontmatter keys whose values should be spellchecked. By default,
                                         no values are spellchecked. Only valid when the `frontmatter` plugin is used.
--reports <file> <file>...               A list of report files to generate. The type of report is based on the
                                         extension of the file. (Supported: .junit.xml and .json)
--config <path>                          A path to a config file.
-h, --help                               Print this help screen.

If you've installed Spellchecker CLI globally, you can simply run spellchecker to invoke the tool. If you used the --save-dev flag, run ./node_modules/.bin/spellchecker from the root directory of your project (or just spellchecker inside an NPM script).

Configuration files

Spellchecker CLI can also read configuration from a JSON or YAML file. By default, it will try to read .spellcheckerrc.yaml, .spellcheckerrc.yml, .spellcheckerrc.json, or .spellcheckerrc.jsonc in the root directory of your project (as determined by pkg-dir). If pkg-dir can't find the project's root directory (e.g. if you've installed Spellchecker CLI globally), it'll look in process.cwd() instead. You can also specify a different path using the --config command line argument.

You can specify any command line option in a config file. Just make sure to use camelcase option names in the config file, e.g. frontmatterKeys instead of frontmatter-keys.

Command line arguments will override any configuration read from a file.


Spellchecker CLI uses globby, which is based on glob, to parse globs. The tool passes the provided list of globs directly to globby. This means that you can, for instance, use ! to negate a glob:

spellchecker --files '**/*.md' '!test/**/*.md' 'test/README.md'

See the node-glob documentation for a full description of glob syntax.


The following retext plugins are supported:

The following remark plugins are supported:

When using the --plugins command-line option, make sure to remove retext- or remark- from the beginning of the plugin name. For example, to use only retext-spell and retext-indefinite-article, run:

spellchecker --files <glob> --plugins spell indefinite-article

Personal dictionaries

Each line in a personal dictionary is treated as a regular expression. You could use this feature to ignore words with a common form but too many possible instances to be included in a personal dictionary. For instance, you could use the regular expression [0-9a-f]{7} to match Git short SHAs.

These regular expressions are case-sensitive. If you want to ignore both the capitalized and uncapitalized version of a word, you should include both versions in the dictionary.

Each regex will be wrapped with ^ and $ before mistakes are tested against it. For example, if "ize" is included in the dictionary, "optimize" and other words that contain "ize" will not be ignored. To match "optimize", you could use the regular expression [A-Za-z]+ize.

A personal dictionary should either be a plaintext file or a JavaScript file. Since Spellchecker CLI uses ES modules, you should use the extension .cjs if you want to use CommonJS module syntax:

// dictionary.cjs
module.exports = ['foo', /^bazz?/];

Otherwise, use ES module syntax:

// dictionary.js or dictionary.mjs
export default ['foo', /^bazz?/];

Note that it isn't possible to ignore multi-word sections of a document using this feature, but only single words or groups of words that you don't want spell-checked.

Generating a personal dictionary

This option is useful for adding Spellchecker CLI to an existing open-source software project with a lot of documentation. Instead of fixing every spelling mistake in one pull request, contributors can gradually remove misspellings from the generated dictionary. It's also helpful to be able to generate a personal dictionary then remove the actual misspellings from the dictionary, leaving behind only project-specific terms.

Built-in dictionaries

The dictionaries subfolder contains base.txt, a basic dictionary of general software terms. It also contains starter dictionaries for Next.js and React projects created using create-next-app and create-react-app respectively. You can provide them as arguments to the spellchecker command:

spellchecker --dictionaries node_modules/spellchecker-cli/dictionaries/nextjs.txt --files ...

Ignore regexes

Each word passed to spellchecker through the --ignore flag will be treated as if it were part of a personal dictionary. These words will be converted into regexes wrapped with ^ and $. During spellchecking, words that match one of these regexes will be ignored.

spellchecker --files README.md --ignore "ize"

In this case, only the literal word "ize" will be ignored, not words that contain it, like "optimize". To match optimize, you could use the regular expression [A-Za-z]+ize.

Note that it isn't possible to ignore multi-word sections of a document using this feature, but only single words or groups of words that you don't want spell-checked.

Gitignore integration

By default spellchecker-cli does not spell-check files that are ignored by .gitignore files. This decreases the amount of files that need to be processed overall, but occasionally this is undesired. To disable this behavior, include the --no-ignore flag.


Spellchecker CLI ignores the contents of inline code blocks and tables in Markdown files (i.e. files with the extension .md, .markdown or .mdx, ignoring capitalization).


Spellchecker CLI can parse Markdown frontmatter when the frontmatter plugin is used. The --frontmatter-keys option can be used to specify a list of top-level keys to extract from the frontmatter. Other top-level keys will be ignored. This is useful for spellchecking only certain parts of the frontmatter. Both YAML and TOML formats are supported using the frontmatter plugin, so the Markdown files you are checking may have a mix of files that use either.

Exclude blocks

If you want to exclude whole blocks in a Markdown file from spellchecking, this could be achieved by using the HTML inline comments <!-- spellchecker-disable --> and <!-- spellchecker-enable -->. Everything between these comments will be removed before proceeding with the spellcheck.


Reports can be generated showing all the issues found in a way that can be read by automation tools or CI/CD systems.

For example, Jenkins and Gitlab CI/CD use JUnit reports, and this allows the creation of those reports, so that the output may be read in the User Interface of those tools. This allows for proper CI/CD integration before deploying static site documentation.

The report type is determined by how the file ends. If the extension ends with .json for example, then it will generate a JSON report.

List of Report types:

  • JSON: ending in .json
  • JUnit: ending in junit.xml (Note, the whole file name may be junit.xml as well)


Run yarn install to install dependencies. Then, run npx ts-node index.ts to run Spellchecker CLI. You can also run yarn spellchecker to run Spellchecker CLI against its own documentation, yarn lint to lint the JavaScript source files, and yarn test to run the test suite.




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