What each tool computes
120 tools · 11 categoriesA hundred and twenty tools, and the specification each one actually implements.
The finding. Thirty of the hundred and twenty answer with a verdict rather than a number, and a pass hides the threshold it applied — which matters because two checkers can disagree on the same pair of colours depending on which specification and which rounding they use. Thirteen do not say which specification they implement at all. Fifteen upload the thing you are testing to somebody else’s server, which decides whether they can touch unreleased work.
What it hands you back
| Tool | Computes | Output | Access | Status |
|---|---|---|---|---|
| Accessibility Insights Guided assessments combining fast pass, assessment and ad-hoc. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-06 |
| AccessMonitor Portuguese government accessibility validator. | WCAG 2.1 AA 2.1 | number | free | maintained 2024-01 |
| AChecker Online checker for WCAG and BITV. | WCAG 2.0 AA 2.0 | verdict offsite | free | maintained 2023-11 |
| ANDI Favelet revealing computed name/role/state. | WCAG 2.1 AA 2.1 · not stated | number | free | maintained 2023-12 |
| ARC Toolkit (TPGi) Browser extension for WCAG audits with ARC engine. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-05 |
| axe DevTools Browser extension and API wrapping axe-core. | WCAG 2.1 AA 2.1 | verdict | freemium | active 2024-08 |
| axe Linter (VS Code) Lints JSX/HTML for accessibility in editor. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-05 |
| axe-core Accessibility engine returning violations per WCAG rule. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-08 |
| eslint-plugin-jsx-a11y ESLint rules for JSX accessibility. | WCAG 2.1 AA + ARIA 2.1 | verdict | free | maintained 2024-04 |
| HTML_CodeSniffer Injectable checker for WCAG 2.0/2.1 and Section 508. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2023-10 |
| IBM Equal Access Accessibility Checker Browser extension and engine with IBM rule set. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-07 |
| Lighthouse Accessibility Audits for accessibility and returns scored report via axe-core. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-07 |
| Nu Html Checker Validates HTML; parser check used as a11y pre-check. | HTML Living Standard | number | free | maintained 2024-07 |
| Pa11y CLI and CI accessibility tester with selectable runners. | WCAG 2.1 AA 2.1 | verdict | free | maintained 2024-03 |
| Siteimprove Accessibility Checker Browser extension highlighting WCAG failures inline. | WCAG 2.1 AA 2.1 · not stated | verdict | freemium | maintained 2024-06 |
| SortSite Crawler checking accessibility, links and standards. | WCAG 2.1 AA 2.1 | verdict | paid | maintained 2024-02 |
| Tenon.io API for accessibility testing with WCAG mapping. | WCAG 2.1 AA 2.1 | verdict offsite | paid | dormant 2021-09 |
| tota11y Visualisation overlay annotating headings, contrast, ARIA. | WCAG 2.1 general 2.1 · not stated | verdict | free | dormant 2019-11 |
| WAVE In-page overlay showing errors, structure and ARIA. | WCAG 2.1 AA 2.1 · not stated | verdict | free | maintained 2024-05 |
| webhint Linting for web best practices including a11y hints. | WCAG 2.1 AA 2.1 · not stated | verdict | free | dormant 2022-10 |
| Coblis — Color Blindness Simulator Simulates images under eight CVD types via upload. | Brettel et al. CVD simulation | number offsite | free | maintained 2023-10 |
| Color Oracle Desktop full-screen CVD filter. | CVD simulation filter | number | free | maintained 2023-08 |
| Colorblindly Browser extension simulating CVD on any webpage. | CVD simulation via CSS filter | number | free | dormant 2021-04 |
| Pilestone Color Blind Simulator Vendor simulator linked to corrective lens product. | CVD simulation · not stated | number offsite | free | maintained 2023-06 |
| Sim Daltonism macOS/iOS real-time CVD filter via camera. | CVD simulation | number | free | maintained 2023-12 |
| Acrolinx Enterprise content governance and terminology checker. | Terminology governance | number offsite | paid | active 2024-06 |
| Alex Catches insensitive and non-inclusive language. | Language sensitivity | number | free | maintained 2024-03 |
| proselint Lints prose for jargon and clichés. | Prose linting | number | free | maintained 2023-11 |
| Vale Lints prose against style guides and checks. | Prose linting (custom rules) | number | free | maintained 2024-07 |
| write-good Lints English for weasel words and passive voice. | Weasel word detection | number | free | maintained 2023-09 |
| Accessible Colors Tests combinations and proposes accessible alternatives. | WCAG 2.1 contrast ratio 2.1 | number | free | maintained 2023-05 |
| Adobe Color Accessibility Palette tool checking contrast and colour-blind safety. | WCAG 2.1 contrast ratio 2.1 · not stated | verdict offsite | freemium | maintained 2024-01 |
| APCA Contrast Calculator (Myndex) Calculates APCA lightness contrast (WCAG 3 draft). | APCA 0.1.9 | number | free | maintained 2024-02 |
| Color.review Checks colour pairs and suggests fixing hues for WCAG. | WCAG 2.1 contrast ratio 2.1 · not stated | verdict | free | dormant 2022-03 |
| Colorable (jxnblk) Minimal WCAG contrast ratio rater. | WCAG 2.1 contrast ratio 2.1 | verdict | free | dormant 2019-06 |
| Contrast Ratio (Lea Verou) Minimal two-colour ratio calculator with WCAG grading. | WCAG 2.1 contrast ratio 2.1 | verdict | free | maintained 2021-10 |
| Contrast-Finder (Tanaguru) Finds nearest passing colour pair from a failing pair. | WCAG 2.1 contrast ratio 2.1 | number | free | maintained 2023-09 |
| Coolors Contrast Checker Palette-linked WCAG contrast checker. | WCAG 2.1 contrast ratio 2.1 · not stated | verdict | freemium | maintained 2023-07 |
| EightShapes Contrast Grid Matrix view of palette contrast across token sets. | WCAG 2.1 contrast ratio 2.1 | verdict | free | maintained 2023-08 |
| Leonardo Generates palettes with WCAG and APCA contrast calculations. | WCAG 2.1 contrast ratio 2.1 APCA 0.1.9 | number | free | maintained 2023-12 |
| Snook Colour Contrast Check Early WCAG contrast checker showing multiple ratios. | WCAG 2.0 contrast ratio 2.0 | verdict | free | dormant 2018-02 |
| Stark Contrast Checker Figma/Sketch plugin and browser contrast checker. | WCAG 2.1 contrast ratio 2.1 | verdict | freemium | active 2024-08 |
| TPGi Colour Contrast Analyser Desktop eyedropper that evaluates contrast including alpha compositing. | WCAG 2.1 contrast ratio 2.1 | verdict | free | maintained 2024-06 |
| WebAIM Contrast Checker Checks foreground/background colours for WCAG contrast compliance. | WCAG 2.1 contrast ratio 2.1 | verdict | free | maintained 2024-09 |
| WhoCanUse Shows WCAG grades across vision types and text sizes. | WCAG 2.1 contrast ratio 2.1 | verdict | free | maintained 2023-11 |
| axe-core Rules Dataset Structured list of axe rules with WCAG mapping. | WCAG SC mapping 2.1 | number | free | maintained 2024-08 |
| Chrome UX Report (CrUX) Field metrics dataset for UX including a11y-adjacent signals. | CrUX metrics | number offsite | free | maintained 2024-08 |
| Color Contrast Dataset (Crowd) Curated pairs of colours with human contrast judgements (placeholder corpus). | Human contrast judgements | number | free | maintained 2023-06 |
| HTTP Archive Corpus of web crawl data including Lighthouse a11y. | Web crawl corpus | number | free | maintained 2024-08 |
| WebAIM Million Annual dataset of top 1M home page a11y failures. | Axe failure corpus | number | free | maintained 2024-02 |
| Carbon Design Tokens Token set and tooling from Carbon Design System. | Carbon tokens | number | free | maintained 2024-07 |
| Diez Cross-platform design token compiler. | Design Tokens | number | free | dormant 2020-03 |
| Primer Tokens GitHub Primer design tokens and utilities. | Primer tokens | number | free | maintained 2024-08 |
| Specify Automates token distribution from Figma to code. | Design Tokens | number offsite | paid | active 2024-07 |
| Style Dictionary Build system transforming design tokens to platforms. | Design Tokens W3C draft | number | free | maintained 2024-07 |
| Supernova Design system platform converting Figma to code. | Design Tokens | number offsite | paid | active 2024-06 |
| Theo Design token transformer from Salesforce UX. | Design Tokens | number | free | dormant 2021-05 |
| Token Transformer Converts Tokens Studio JSON to Style Dictionary format. | Design Tokens W3C | number | free | maintained 2023-08 |
| Tokens Studio for Figma Figma plugin managing design tokens and syncing to Git. | Design Tokens W3C draft | number | freemium | active 2024-08 |
| W3C Design Tokens Spec Specification reference for design tokens format. | Design Tokens Specification draft | number | free | maintained 2024-02 |
| Autocomplete Attribute Checker Tests browser autocomplete token support. | HTML autocomplete attribute | number | free | maintained 2023-09 |
| Form Ally Linter Lints forms for label, fieldset and autocomplete issues. | WCAG 2.1 label checks 2.1 | number | free | maintained 2023-11 |
| GOV.UK Design System Form Validation Form validation patterns for UK government services. | GOV.UK Design System | number | free | maintained 2024-07 |
| HTML5 Input Types Tester Shows rendering of HTML5 input types across browsers. | HTML Living Standard input types | number | free | maintained 2023-08 |
| Input Mask Accessibility Checker Tests masked inputs for screen-reader announcement. | ARIA input mask | number | free | dormant 2022-05 |
| USWDS Form Components Accessible form component reference and validator. | USWDS 3.0 3.0 | number | free | maintained 2024-07 |
| W3C ARIA Validator Validates ARIA attributes in markup including forms. | WAI-ARIA 1.2 1.2 | number | free | maintained 2024-07 |
| WAI-ARIA APG Form Patterns Reference patterns for accessible form widgets. | WAI-ARIA 1.2 1.2 | number | free | maintained 2024-07 |
| axe Accessibility Inspector Inspects accessibility tree alongside axe results. | Accessibility tree | number | free | maintained 2024-03 |
| BrowserStack Responsive Cloud responsive testing across real devices. | Responsive cloud | number offsite | paid | active 2024-07 |
| Chrome DevTools Browser inspector measuring layout, colour and a11y tree. | CSS/AX Tree inspection | number | free | maintained 2024-08 |
| Dimensions (Figma plugin) Measures distances between Figma layers. | Figma measurement | number | free | maintained 2023-12 |
| Figma Measure Generates spec measurements for Figma handoff. | Spec generation | number | free | maintained 2023-09 |
| Firefox Accessibility Inspector Shows accessibility tree and contrast in Firefox. | Accessibility tree | number | free | maintained 2024-07 |
| Measure-it Draws ruler to measure page elements. | Pixel measurement | number | free | dormant 2020-01 |
| PerfectPixel Overlays semi-transparent image for pixel comparison. | Pixel overlay comparison | number | free | maintained 2023-10 |
| Pesticide Outlines every element to reveal layout. | Layout outline | number | free | maintained 2023-08 |
| Pixel Perfect (Chrome) Overlay design image for pixel comparison in Chrome. | Pixel overlay | number | free | maintained 2023-10 |
| Polypane Dev browser with a11y and contrast panes. | Accessibility pane | verdict | paid | active 2024-08 |
| Responsively App Open-source dev browser for responsive design. | Multi-viewport | number | free | maintained 2024-05 |
| Sizzy Synced multi-viewport browser for responsive inspection. | Multi-viewport | number | paid | active 2024-07 |
| VisBug Inspect and edit any page's visual design. | Visual inspection | number | free | maintained 2023-06 |
| Window Resizer Resizes viewport to preset dimensions. | Viewport sizing | number | free | maintained 2023-11 |
| Datayze Readability Analyzer Analyzes text for readability and suggests improvements. | Flesch-Kincaid | number | free | maintained 2023-12 |
| Gunning Fog Calculator Dedicated Gunning Fog index calculator. | Gunning Fog | number | free | maintained 2023-09 |
| Hemingway App Editor scoring readability by grade and sentence complexity. | Automated Readability Index | number | freemium | maintained 2024-02 |
| Readability Formulas Collection of readability calculators and explanations. | Flesch Reading Ease | number | free | maintained 2023-10 |
| Readable Scores text on Flesch-Kincaid, Gunning Fog, SMOG and others. | Flesch-Kincaid Gunning Fog SMOG | number offsite | paid | active 2024-07 |
| textstat Python library computing readability metrics. | Flesch-Kincaid | number | free | maintained 2024-07 |
| WebFX Readability Tool Free readability checker with Flesch-Kincaid score. | Flesch-Kincaid | number | free | maintained 2024-03 |
| JAWS Commercial Windows screen reader. | IAccessible2/UIA | number | paid | maintained 2024-07 |
| Narrator Built-in Windows screen reader. | UIA | number | free | maintained 2024-07 |
| NVDA Free Windows screen reader. | IAccessible2/UIA | number | free | maintained 2024-08 |
| TalkBack Android screen reader. | AccessibilityNodeInfo | number | free | maintained 2024-05 |
| VoiceOver Built-in macOS/iOS screen reader. | AX API | number | free | maintained 2024-06 |
| A11ySupport.io Tests which AT support which ARIA/HTML features. | AT support data | number | free | maintained 2023-11 |
| ARIA APG Authoring practices for ARIA patterns. | WAI-ARIA 1.2 1.2 | number | free | maintained 2024-07 |
| Can I use Browser support tables for web features including a11y. | Browser support | number | free | maintained 2024-08 |
| HTML Standard (WHATWG) Living HTML specification. | HTML Living Standard | number | free | maintained 2024-08 |
| Inclusive Design Principles Reference principles for inclusive design decisions. | Inclusive Design Principles | number | free | maintained 2023-09 |
| MDN Web Docs Reference for HTML/CSS/JS and accessibility attributes. | HTML Living Standard | number | free | maintained 2024-08 |
| W3C Markup Validation Service Validates HTML/CSS against specifications. | HTML Living Standard | number | free | maintained 2024-07 |
| WCAG Quick Reference (W3C) Filterable reference for WCAG success criteria. | WCAG 2.1 2.1 | number | free | maintained 2024-07 |
| Axis-Praxis Variable font specimen and axis tester. | OpenType variations | number | free | maintained 2023-06 |
| Capsize Trims whitespace from text bounding boxes via font metrics. | Font metrics trimming | number | free | maintained 2023-09 |
| Fluid Type Scale Calculator Generates clamp-based fluid type scales. | CSS clamp fluid type | number | free | maintained 2023-09 |
| Font Gauntlet Variable font proofing and QA web app. | OpenType QA | number | freemium | maintained 2023-07 |
| FontBakery Font quality checker with 200+ checks. | Google Fonts spec | verdict | free | maintained 2024-07 |
| FontDrop Drag-and-drop OpenType table inspector. | OpenType tables | number | free | maintained 2023-11 |
| Glyphhanger Subsetting and glyph inspection via font file. | Glyph coverage | number | free | maintained 2023-05 |
| Modular Scale Calculates typographic scales from ratio and base. | Modular scale | number | free | maintained 2023-10 |
| Samsa Variable font playground showing axis interpolation. | OpenType variations | number | free | maintained 2023-08 |
| Type Scale Visual type scale preview with CSS output. | Type scale preview | number | free | maintained 2022-08 |
| Wakamai Fondue Inspects variable font tables and features. | OpenType tables | number | free | maintained 2024-03 |
| WhatFontIs Identifies fonts from uploaded images. | Font identification · not stated | number offsite | freemium | maintained 2024-01 |
| Mapbox Wayfinding Indoor/outdoor wayfinding map SDK. | Mapbox Streets | number offsite | paid | active 2024-08 |
| NaviLens Accessible wayfinding codes for blind navigation. | NaviLens code | number | freemium | active 2024-07 |
| SignAgent Wayfinding signage inventory and compliance platform. | ADA Signage · not stated | number offsite | paid | active 2024-06 |
| Transit Maps Maker Tool for designing transit wayfinding maps. | Transit wayfinding · not stated | number | freemium | maintained 2023-05 |
| Wayfound Cloud wayfinding CMS for signage networks. | Wayfinding signage CMS · not stated | number offsite | paid | active 2024-03 |
30 of 120 return a verdict rather than a number. 13 do not state which specification they implement. 15 send the thing you are testing to another server. 11 are dormant and kept deliberately. None is an affiliate link.
Source. each tool’s own pages, repositories and changelogs · various · recorded per row · retrieved 2026-08-26. This collection is derived · one register.