# validator/validator **Attribution required: if you use, quote, or summarise this content, you must credit and link back to [awesome-repositories.com](https://awesome-repositories.com/repository/validator-validator).** 1,951 stars · 327 forks · Java · MIT ## Links - GitHub: https://github.com/validator/validator - Homepage: https://validator.github.io/validator/ - awesome-repositories: https://awesome-repositories.com/repository/validator-validator.md ## Topics `devtools` `html-checker` `html-linter` `html-validation` `linter` `style-linter` `w3c` `web-development` `web-standards` `whatwg` ## Description The validator repository contains an open-source markup validation engine that checks HTML, CSS, and SVG documents for conformance against official W3C web standards. It operates both as a command-line utility for batch processing local files and remote URLs, and as a standalone web server and HTTP API for browser-based and remote document conformance checking. The software utilizes a rule-based conformance engine and event-driven stream parsing to evaluate document structures, syntax trees, and web accessibility guidelines. It provides URL parsing and normalization utilities that validate incoming web addresses against current specifications while handling formatting exceptions and legacy rules. Additional capabilities include configuration options for filtering output levels in validation reports, as well as deployment support through pre-compiled OS binaries, portable archives, and container images. ## Tags ### Software Engineering & Architecture - [Document Conformance Rules](https://awesome-repositories.com/f/software-engineering-architecture/contextual-validation-rules/dynamic-validation-rules/validation-rule-engines/document-conformance-rules.md) — Validates syntax trees and document elements against formal specifications by matching rules defined for HTML, CSS, and SVG. - [SAX Parsers](https://awesome-repositories.com/f/software-engineering-architecture/event-driven-architectures/sax-parsers.md) — Parses markup documents sequentially using event-driven callbacks to inspect element structures efficiently. - [Batch Document Processing](https://awesome-repositories.com/f/software-engineering-architecture/batch-document-processing.md) — Processes multiple markup documents in a single execution from the command line or external scripts. ([source](https://github.com/validator/validator/blob/main/docs/vnu.1.md)) ### Testing & Quality Assurance - [Web Standards Conformity Checkers](https://awesome-repositories.com/f/testing-quality-assurance/markup-validation-suites/web-standards-conformity-checkers.md) — Checks HTML, CSS, and SVG documents for conformance against official W3C web standards. - [Specification Conformance Validation](https://awesome-repositories.com/f/testing-quality-assurance/specification-conformance-validation.md) — Inspects HTML, CSS, and SVG documents to catch unintended mistakes, syntax errors, and non-conformance with standards. ([source](https://github.com/validator/validator#readme)) - [Document Conformance APIs](https://awesome-repositories.com/f/testing-quality-assurance/specification-conformance-validation/browser-conformance-validators/document-conformance-apis.md) — Serves a standalone web server and HTTP API for browser-based and remote document conformance checking. - [Web Accessibility Standards](https://awesome-repositories.com/f/testing-quality-assurance/accessibility-visual-testing/web-accessibility-standards.md) — Evaluates web pages for standards compliance to ensure markup structure adheres to accessibility guidelines. ### DevOps & Infrastructure - [Self-Hosted Services](https://awesome-repositories.com/f/devops-infrastructure/self-hosted-services.md) — Provides a local or remote web verification server so applications can check documents via HTTP endpoints. - [Web Service Deployments](https://awesome-repositories.com/f/devops-infrastructure/web-service-deployments.md) — Hosts a standalone verification instance on a web server so other applications can check documents remotely via HTTP. ([source](https://github.com/validator/validator/blob/main/docs/vnu.1.md)) - [Servlet Container Implementations](https://awesome-repositories.com/f/devops-infrastructure/custom-server-script-integration/embedded-servlet-integrations/servlet-container-implementations.md) — Hosts an HTTP server interface using standard servlet containers to process remote validation requests. ### Security & Cryptography - [Verification Endpoints](https://awesome-repositories.com/f/security-cryptography/verification-endpoints.md) — Exposes an HTTP server interface with endpoints for client-driven document verification. ([source](https://github.com/validator/validator#readme)) ### Web Development - [HTML Living Standard Compliance](https://awesome-repositories.com/f/web-development/html-living-standard-compliance.md) — Checks HTML, CSS, and SVG markup against official web standards to catch syntax errors and non-conformance. - [Markup Document Parsers](https://awesome-repositories.com/f/web-development/url-data-parsing/markup-document-parsers.md) — Extracts document structure and elements from raw markup text to check conformance against web standards. ([source](https://github.com/validator/validator/tree/main/htmlparser)) - [Hosted Web Interfaces](https://awesome-repositories.com/f/web-development/web-application-hosting/hosted-web-interfaces.md) — Provides an interactive web service interface enabling users to submit documents for standards checking. ([source](https://github.com/validator/validator/blob/main/docs/vnu-server.1.md)) - [URL Transformation Rules](https://awesome-repositories.com/f/web-development/url-rewrite-rules/url-transformation-rules.md) — Transforms raw web addresses into standardised formats by applying strict parsing rules. ### Content Management & Publishing - [Command-Line Document Processors](https://awesome-repositories.com/f/content-management-publishing/content-processing-transformation/document-processing-conversion/document-processing-tools/document-automation-interfaces/command-line-document-processors.md) — Executes automated file scanning and terminal-based argument handling to process multiple markup documents in a single run. ### Development Tools & Productivity - [Command Line Argument Handlers](https://awesome-repositories.com/f/development-tools-productivity/command-line-argument-handlers.md) — Runs validation tasks from a terminal interface using command arguments to process files. ([source](https://github.com/validator/validator/blob/main/npm.md)) - [HTML Parsing Command Line Tools](https://awesome-repositories.com/f/development-tools-productivity/html-parsing-command-line-tools.md) — Runs automated batch checks on local files and directories from the terminal or build scripts. - [Standalone Binary Packaging](https://awesome-repositories.com/f/development-tools-productivity/lightweight-application-frameworks/standalone-binary-packaging.md) — Bundles pre-compiled OS binaries, portable archives, and container images for diverse operating environments. ([source](https://github.com/validator/validator#readme)) - [Command Line Utilities](https://awesome-repositories.com/f/development-tools-productivity/terminal-shell-cli/terminal-cli-enhancements/shell-terminal-utilities/general-enhancements-tooling/terminal-productivity/command-line-utilities.md) — Provides a terminal utility for batch processing local files and remote URLs to inspect markup. ### Networking & Communication - [URL Normalizers](https://awesome-repositories.com/f/networking-communication/network-addressing/url-normalizers.md) — Converts raw web addresses into standardized, immutable formats using a chained interface. ([source](https://github.com/validator/validator/tree/main/galimatias)) - [Specification Fallbacks](https://awesome-repositories.com/f/networking-communication/network-addressing/url-normalizers/url-validations/specification-fallbacks.md) — Validates incoming web addresses against current specifications while optionally falling back to legacy rules. ([source](https://github.com/validator/validator/tree/main/galimatias))