# Install vnu with Homebrew Nu Markup Checker: command-line and server HTML validator. Version 26.7.22 via Homebrew; verified 2026-07-23. ## Install ```sh sudo av install brew:vnu ``` Additional install commands: ### macOS - Homebrew (100%): ```sh brew install vnu ``` Evidence: local Homebrew formula metadata ## Package facts - **Package key:** brew:vnu - **Package manager:** Homebrew - **Package manager page:** - **Version:** 26.7.22 - **Source summary:** Nu Markup Checker: command-line and server HTML validator - **Homepage:** - **Upstream docs:** - **License:** MIT - **Source archive:** - **Last updated:** 2026-07-23T09:59:29Z - **Generated:** 2026-07-25T07:20:51+00:00 ## Executables - vnu (cli) - vnu (alias) ## Dependencies - openjdk ## Install behavior - Post-install hook: not defined - Bottle: available on all ## Freshness - Page generated: 2026-07-25 - Package-manager version: 26.7.22 - Package-manager updated: 2026-07-23 - Local data: ok - Upstream repository: https://validator.github.io/validator/ - info: Release/tag comparison is only available for GitHub repositories. ## Project history and usage The Nu Html Checker, commonly invoked as `vnu`, is the modern HTML, CSS, and SVG checking engine associated with validator.nu and W3C's `validator.w3.org/nu` service. It is used both as a command-line checker for local files and as a deployable HTTP validation service. ### Project history The project grew out of the HTML5-era validator.nu checker work and became the backend behind `html5.validator.nu`, `validator.w3.org/nu/`, and the HTML5 facet of the legacy W3C validator. A W3C validator mailing-list announcement in August 2014 described a new Nu Markup Checker release that packaged the same backend as a portable `vnu.jar` and as a WAR file for servlet containers. The current README describes the project as the Nu Html Checker and says release 20.6.30, dated 30 June 2020, was the final major version-numbered release; after that, users are directed to the production-ready release named `latest`. The same README documents a broad packaging model: standalone runtime images, `vnu.jar`, `vnu.war`, a container image, and integrations with build tools. ### Adoption history vnu's adoption is tied to the web standards ecosystem rather than to a single application. It is the checker behind a public W3C validation endpoint, appears in frontend build workflows through Grunt, Gulp, Maven, npm, containers, and direct CLI use, and is deliberately described by its own about page as an evolving checker rather than a formal pass/fail certification service. ### How it is used Developers use `vnu` to catch unintended mistakes in HTML, CSS, and SVG, either by running the jar or native runtime against files, directories, or URLs, or by starting a local/server-side HTTP checker. The README's examples cover command-line batch checking, a standalone web server, servlet deployment through a WAR file, an HTTP client for a local or remote checker service, and containerized operation. ### Why package nerds care For package users, vnu is important because it turns the constantly evolving web-platform conformance checker into a local, scriptable artifact. That makes it usable in CI, static-site builds, editor tooling, and regression suites without sending every document to a public validator service. ### Timeline - 2014-08-27: W3C announces a Nu Markup Checker release with `vnu.jar` batch checking and WAR deployment. - 2018: GitHub releases show standalone jar and WAR distributions used for command-line and service deployments. - 2020-06-30: Release 20.6.30 becomes the final major version-numbered release. - 2021: The project publishes a GitHub container package for the checker. - Present: Upstream directs production users to the continuously updated release named `latest`. ### Related projects - Related projects and surfaces include validator.nu, W3C Markup Validation Service, `validator.w3.org/nu`, the validator.nu HTML parser, and build-tool front ends such as Grunt, Gulp, and Maven HTML-validation plugins. ### Sources - Nu Html Checker README: https://raw.githubusercontent.com/validator/validator/master/README.md - Nu Html Checker about page: https://validator.github.io/validator/site/nu-about.html - Nu Html Checker releases: https://github.com/validator/validator/releases - W3C www-validator announcement, 2014-08-27: https://lists.w3.org/Archives/Public/www-validator/2014Aug/0026.html ## Security Notes No matching local secret-handling manifest was found for vnu. Nucleus package metadata is still published here so future coverage has a stable package URL. ## Source Database Details - **Source Database:** Homebrew formula API - **Tap:** homebrew/core - **Full Name:** vnu - **Version Scheme:** 1 - **Revision:** 0 - **Bottle Stable Root URL:** - **Deprecated:** no - **Disabled:** no - **Keg Only:** no - **URL Keys:** stable ## Related links - [Source-control packages](https://www.automicvault.com/pkg/source-control-tools/) - Belongs to a source-control command family. - [Terminal utility packages](https://www.automicvault.com/pkg/terminal-utilities/) - Matched terminal and command-line workflow metadata. - [Text processing packages](https://www.automicvault.com/pkg/text-processing-tools/) - Matched text, document, or structured-data processing metadata. - [Developer build packages](https://www.automicvault.com/pkg/developer-build-tools/) - Matched build, compiler, generator, or developer workflow metadata. - [openjdk](https://www.automicvault.com/pkg/brew/openjdk/) - Runtime dependency declared by Homebrew. - [templ](https://www.automicvault.com/pkg/brew/templ/) - Shares av.db curated category or tags: cli, developer-tools, html, web-development. - [adr-viewer](https://www.automicvault.com/pkg/brew/adr-viewer/) - Shares av.db curated category or tags: cli, developer-tools, html. - [aha](https://www.automicvault.com/pkg/brew/aha/) - Shares av.db curated category or tags: cli, developer-tools, html. - [angular-cli](https://www.automicvault.com/pkg/brew/angular-cli/) - Shares av.db curated category or tags: cli, developer-tools, web-development. - [ansifilter](https://www.automicvault.com/pkg/brew/ansifilter/) - Shares av.db curated category or tags: cli, developer-tools, html. - [anycable-go](https://www.automicvault.com/pkg/brew/anycable-go/) - Shares av.db curated category or tags: cli, developer-tools, server. - [arabica](https://www.automicvault.com/pkg/brew/arabica/) - Shares av.db curated category or tags: cli, developer-tools, html. - [atuin-server](https://www.automicvault.com/pkg/brew/atuin-server/) - Shares av.db curated category or tags: cli, developer-tools, server. - [vnu-jar](https://www.automicvault.com/pkg/npm/vnu-jar/) - Executable or command metadata overlaps with this package. Shared terms: checker, cli, developer, developer-tools, html. - [gwt](https://www.automicvault.com/pkg/brew/gwt/) - Local package facts share a topical domain. Shared terms: cli, developer, developer-tools, development, openjdk. ## Combined YAML source View the package source record on GitHub. [combined/vnu.yml](https://github.com/automic-vault/db/blob/main/combined/vnu.yml) ## Sources - Nucleus package database - Geiger risk classifier - package-page enrichment - curated package history - package version freshness - av.db category and tag curation - package relationship graph - cross-ecosystem install command graph