Colour Contrast Checker
An open-source extension that checks the contrast between two colours against WCAG 2.
Why it's a strong pick
Colour Contrast Checker does one job and asks for little. Its only permission is activeTab. It is open source under the MIT license, and its code is public on GitHub. It uses Manifest V3. The latest release, v2.1.0, came on 11 September 2026.
What it does
Click the icon on a page and a 475px panel opens at the bottom of the tab. Pick a text colour and a background colour, and the panel shows the contrast ratio and grades it against WCAG 2 AA and AAA, for normal and large text. You can type colours or sample them from the page with the eyedropper.
Key features
- Live grades. See the ratio and AA and AAA results for normal and large text.
- Synced inputs. Hex, RGB and HSL values stay in step.
- Eyedropper. Sample a colour from the page, with a magnifying loupe.
- Saved pairs. Keep up to five colour pairs.
- Reverse button. Swap text and background.
- Share link. Open the pair in the companion web app.
Who it's for
Colour Contrast Checker is for designers, front-end developers and accessibility reviewers who check text and background pairs. It suits anyone who wants a quick answer on one pair of colours.
What permissions does Colour Contrast Checker ask for?
Only activeTab, per the README and the manifest. That lets it work on the tab where you click the icon. The panel and eyedropper do not work on chrome:// pages, the Web Store or file:// pages, and show an error there.
Does Colour Contrast Checker collect my data?
The README says only activeTab is requested, and it states no data practices. That means the developer has not described what, if anything, is collected. We could not read the developer's privacy policy when we checked, so read it before installing, and review the single permission in Chrome's extension settings.
Does it check a whole page?
No. It checks one colour pair at a time. You choose the colours with the eyedropper or the inputs, then it shows the result for that pair only. For a full-page review, use it next to a page-level tool such as Accessibility Insights for Web.
Does it work on text over images?
Only with care. The eyedropper samples pixels, so text over an image or a gradient needs your judgement. Sample the weakest spot, where the text is hardest to read, and test that pair. The tool checks one colour pair at a time, so repeat the check for each area that looks risky.
FAQ
Is it open source? Yes, under the MIT license.
Which standard does it use? WCAG 2, at levels AA and AAA.
Does it need a recent Chrome? Yes. The README says Chrome 111 or later.
Good to know
The repo has a single release so far, so its update pace is unproven. For a long audit, save your key colour pairs in the five slots, and note the results in your own file.
Other accessibility tools to compare
Colour Contrast Checker is one of 6 picks in our accessibility tools guide:
- Read Aloud: Reads web pages and PDFs out loud, with browser and cloud voices, speed settings and text highlighting. Open source.
- Vimium: Browse with keyboard commands: scroll, click links with hints and switch tabs. Open source.
- Accessibility Insights for Web: Checks a page for accessibility problems using the axe-core engine. Open source.
- axe DevTools: Deque’s automated accessibility checker, with a free version and a paid Pro plan.
- WAVE Evaluation Tool: WebAIM’s checker that overlays accessibility issues on the page. No price listed.
This is a third-party extension, not built or maintained by Xplorekit. We link to the official Chrome Web Store listing — install and permissions are entirely between you and the extension's own publisher.