Need more than a rule playground? Vale CMS authors full Vale projects: config, rules, vocabularies, tests, and Git-backed changes.

Vale is a linter for prose

A command-line tool that brings code-like linting to your writing. Enforce a consistent editorial style across every doc, in any format—entirely offline.

Get started Star on GitHub

Setting up with an agent?

Open in Claude Open in ChatGPT Agent skills

Thanks to Claude for Open Source.

bash — vale

$ vale README.md

README.md

4:3 error Did you really mean 'existant'? Vale.Spelling

6:12 warning Use 'use' instead of 'utilize'. Microsoft.Vocab

9:1 suggestion In general, use active voice. write-good.Passive

✖ 1 error, 1 warning and 1 suggestion in 1 file.

Sponsor spotlight

Mintlify

Funds Vale's development, and ships it as a built-in CI check.

Shipping in the documentation pipelines of

Why Vale

Linting built for the way you write

The precision of a code linter, applied to prose—so quality and consistency stop being a manual review step.

Markup-aware

Lints prose in Markdown, AsciiDoc, reStructuredText, and HTML—ignoring the syntax.

# Installation

You can **utilize** Vale to lint [prose](/docs)—it ignores syntax like `code` and URLs.

warning Use 'use' instead of 'utilize'. Microsoft.Vocab

How scopes work

Private by design

Runs entirely offline. Your content is never sent to a remote server for processing or training.

Fast, single binary

Built in Go with no runtime dependencies. A 2,800-page Markdown corpus, 82 rules, in under 20 seconds.

$ vale docs/

# One binary. Nothing else to install.

What makes it fast

Code-aware

Reads comments and docstrings with tree-sitter grammars, in more than twenty languages.

func Get(id string) (*Record, error) {

// It utilizes the cache when possible.

key := "// not a comment"

}

warning Use 'uses' instead of 'utilizes'. Microsoft.Vocab

Inside the grammar

Extensible

Write your own rules in YAML—no plugins to compile. Match your brand voice, share across a team.

# styles/Brand/Terms.yml

extends: existence

message: "Avoid '%s'."

All twelve extension points

Runs everywhere

One tool for macOS, Windows, and Linux—MIT-licensed, open source, and actively maintained.

Style guides included

Ready-made Microsoft, Google, and other popular guides, plus community packages.

StylesPath = styles

MinAlertLevel = suggestion

[*.md]

BasedOnStyles = Vale, Microsoft, Google

ValeMicrosoftGooglewrite-goodproselintRed Hat

Vale for agents

Your assistant writes the docs. Something should check them.

A model will write you plausible prose and plausible linter rules with equal confidence. Vale is what tells it which of those actually hold up—in the same turn, not in review.

Free

Skills

Setup, fixing alerts, triaging a noisy first run, vocabularies, and CI. Each one runs the CLI in your repository and ends with a report.

Browse the skills

Free

Edit hook

Lints each prose file the moment your assistant writes it and hands back only the error-level alerts, so mistakes get fixed in the same turn they were made.

See the hook

Vale CMS

MCP server

The engine itself, as tools an assistant can call — so a rule it writes gets compiled, tested, and costed before it reaches your repository.

What it can check

All three, in Claude Code

Other clients can read skills/ directly.

/plugin marketplace add vale-cli/agent-tools
/plugin install vale@agent-tools

The skills and the hook need nothing but the Vale binary. The MCP server is the one paid piece — it runs on Vale CMS, and everything else works without it.