errata-ai / vale-cli
Vale is a free, MIT-licensed command-line linter that brings code-like, customizable style checking to prose. It is designed to enforce a shared editorial standard across documents, authors, editors and CI pipelines, rather than act as a general-purpose grammar tutor.
At a Glance
- Documentation teams and technical writers
- Software companies and developer-tool organizations
- Open-source projects and maintainers
- Engineering teams using documentation CI/CD
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AI Tools by errata-ai / vale-cli
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Vale
Prose Linter for Developers
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Latest News
Vale v3.19.0: MDX JSX children are linted as Markdown, with component class scopes and improved MDX coverage.
Vale v3.18.0: expanded format support, meta scope, plain-progress output and per-package CI logging.
Vale v3.17.1 maintenance release.
Vale v3.17.0: major performance improvements, inline scopes and style-level severity changes.
Products & Services
The core offline, cross-platform Go command-line linter for prose; it parses markup, applies configurable YAML rules and emits errors, warnings and suggestions.
Hosted authoring layer for a complete Vale project, including .vale.ini configuration, rules, vocabularies, dictionaries, filters, views and templates; it runs the real Vale engine live and exposes a hosted MCP server for assistants.
Browser-based project associated with the Vale ecosystem; the repository documentation describes it as a related project and the site identifies DigitalOcean as its infrastructure host.
Rust implementation of the Language Server Protocol for Vale, enabling diagnostics in LSP-capable editors.
Market Position
Vale positions itself as a code-linter-style tool for editorial consistency, differentiated from general writing aids such as Grammarly by letting teams define and enforce their own rules. Its main advantages are offline execution, markup and context awareness, broad format/language coverage, extensibility and CI/editor integration; it competes with general grammar checkers and other prose/style linters while emphasizing document structure and team-specific standards.
Leadership
Founders
Joseph Kato
Open-source software developer with interests in natural-language processing, data science and collaborative writing; he has a mathematics degree, works primarily with Go, Python and Rust, wrote the Go NLP library prose, and is identified by the project as Vale's sole developer/creator and maintainer.
Founding Story
Vale began from the desire for a spell-checking and style tool that understood markup such as AsciiDoc, Markdown and reStructuredText and could be incorporated straightforwardly into continuous-integration systems. Kato introduced Vale publicly with the v1.0.0 announcement in September 2018, positioning it as a prose equivalent of a code linter: a framework for teams to encode and enforce their own style rules rather than a tool that supplies one universal notion of correct writing.
Business Model
Revenue Model
The core Vale CLI, engine and styles are free and MIT licensed. Project support comes from GitHub Sponsors, Open Collective, grants and organizational sponsorships; Vale CMS adds paid hosted authoring and MCP access on top of the free CLI.
Pricing Tiers
Free forever; the CLI is open source, while CMS's free browser experience supports opening folders/zips, live linting and read-only sample-project browsing.
One person; full editor, GitHub/GitLab repository editing and pull requests, hosted MCP server and Discord support; one-month free trial.
Flat domain-wide coverage with no per-seat count, including automated accounts, MCP and priority private-Discord support; one-month free trial.
Target Markets
- Documentation teams and technical writers
- Software companies and developer-tool organizations
- Open-source projects and maintainers
- Engineering teams using documentation CI/CD
- Enterprises with brand, legal, compliance or editorial style guides
- Authors working in VS Code, JetBrains, Neovim, Sublime Text, Zed, Emacs, Obsidian and other supported editors
- Enforcing a shared editorial or brand style guide across multiple authors
- Linting technical documentation and knowledge bases
- Checking prose in pull requests and continuous-integration pipelines
- Linting documentation embedded in source-code comments and doc comments
- Local, privacy-preserving offline style checking
- Authoring and validating Vale rules, vocabularies and dictionaries with an AI assistant through MCP
- Amazon Web Services
- Microsoft
- GitLab
- Grafana Labs