Color Contrast Checker
Free, no signup. Compare foreground and background colors against WCAG 2.2 AA and AAA, get the closest practical hex alternatives that pass, or check a live URL's real rendered contrast.
Check a URL's rendered contrast
Loads the page in a metered headless browser and runs axe-core's color-contrast rule against the real computed styles — the resolved foreground, background, opacity, inherited color, and CSS variables after the cascade, not a static-HTML color guess. This is the same Browser-Rendering pipeline the AccessibilityWeb accessibility means designing sites so people with disabilities can use them, per the W3C's WCAG guidelines. It overlaps with SEO in specific, checkable ways — alt text, heading structure, descriptive link text, captions, and page speed all serve both audiences — but Google has said accessibility itself is not a ranking factor, and most WCAG success criteria (keyboard focus order, ARIA live regions, form labels) have no SEO effect at all. Tester uses, filtered to just contrast findings.
Checks run from our server; we fetch the URL you enter and don't keep the results. This launches a metered browser audit shared with the Accessibility Tester's rendering budget, so it is rate-limited per visitor and per target site. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.
Runs entirely in your browser — nothing you paste is uploaded or stored. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.
Palette audit
Paste CSS variables, token declarations, or a hex list. The matrix checks every color as text against every other color as a background.
Site passport Local context for this saved site
Local data
Saved targets, named lists, and recent check summaries remain only in this browser.
Rate this tool
Example
Example data — engine-verified result
#777777 foreground on #FFFFFF: 4.48:1
- Pass: AA large text and UI (3:1).
- Below: AA normal text and AAA large text (4.5:1), plus AAA normal text (7:1).
- Nearest AA normal-text alternative:
#767676, one step darker, at 4.54:1.
How it works
Paste mode calculates contrast from the WCAG relative-luminance formula, not by simply comparing RGB values. The suggestions preserve the foreground hue and saturation while walking its lightness toward the nearest passing color, then verify the rounded hex result. The URL mode above instead loads the page in a metered headless browser and reads each element's actual computed color and background after the CSS cascade resolves — the only way to catch contrast failures caused by inherited color, semi-transparent backgrounds, CSS variables, or the browser's default stylesheet, none of which a pasted color list can see.
Use the right rule
Normal-size text needs 4.5:1 for AA. Large text (at least 24px regular or 18.66px bold) and non-text UI indicators need 3:1. Color should never be the only way to communicate a state.
Frequently asked questions
What contrast ratio do I need?
WCAG AA requires 4.5:1 for normal text and 3:1 for large text and non-text UI components. AAA requires 7:1 for normal text and 4.5:1 for large text.
Does this prove my page is accessible?
No. It checks color pairs, not typography, focus states, images of text, or (in paste mode) real rendered backgrounds. Treat it as a design-time check and test the finished interface too.
Where does my palette go?
In paste mode it stays in the browser — paste CSS custom properties, Tailwind-style name/value tokens, or a loose list of hex colors. Only the URL mode sends anything to our server, and that is the public page address you enter, not a palette.
How is the URL mode different from pasting colors?
Pasted colors give you exact math on the pair you type. The URL mode loads the real page in a metered headless browser and reads each element's actual computed color and background after the CSS cascade, inheritance, opacity, and browser defaults are resolved — the only way to get a genuine contrast verdict for a live page, since a static-HTML color guess can be wrong.
Feature requests for Color Contrast Checker
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À propos de l’outil
Vérifiez le contraste WCAG 2.2 d’une palette ou d’une URL rendue, trouvez des couleurs de premier plan proches qui passent et auditez les jetons CSS dans votre navigateur.
Fonctionnalités
- Calcul exact du contraste pour chaque paire de couleurs collée.
- Alternatives hexadécimales proches qui respectent les seuils AA et AAA.
- Mode URL avec styles réellement calculés dans un navigateur headless.
- Matrice de palette et constats de contraste non textuel.
Fonctionnement
Le mode palette calcule la luminance relative et les rapports WCAG localement. Le mode URL charge la page dans un navigateur mesuré, lit les styles calculés et exécute la règle de contraste axe-core sur le rendu réel.
Limites
- Le mode palette ne rend pas la page et ne voit pas les états focus, survol ou désactivé.
- Le verdict dépend du rendu réel, de l’opacité, de l’héritage et des variables CSS.
- Un contraste correct ne prouve pas à lui seul l’accessibilité de toute l’interface.
Questions fréquentes
Ce contrôle prouve-t-il que ma page est accessible ?
Non. Il vérifie les paires de couleurs, mais pas la typographie, le focus, les images de texte ni tous les parcours clavier.
Quel rapport de contraste faut-il ?
AA demande 4,5:1 pour le texte normal et 3:1 pour le grand texte et les composants non textuels ; AAA demande respectivement 7:1 et 4,5:1.
Où va ma palette ?
Les couleurs collées restent dans le navigateur. Seul le mode URL envoie l’adresse publique saisie au serveur de rendu.
Comment le mode URL diffère-t-il du collage ?
Il lit les couleurs réellement calculées après cascade, héritage et opacité, au lieu d’estimer un rendu HTML statique.