WCAG Contrast Checker

No. The browser decodes the selected image and reads its pixels locally with Canvas. The screenshot, sampled colors, and audit report are not sent to CanDoYa. The tool also works with pasted clipboard images, so you do not need to save a temporary file first.

Yes. The checker is free to use without an account or a usage limit. You can test exact hex colors, load screenshots, sample as many pairs as needed, and copy each audit report directly from the browser.

It accepts PNG, JPEG, WebP, GIF, and AVIF images up to 20 MB and 32 megapixels. Very large screenshots use substantial browser memory, so resize them first. The checker reads the first displayed frame of an animated image.

Normal text needs at least 4.5:1. Large text needs at least 3:1, and meaningful interface components and graphical objects also use a 3:1 threshold against adjacent colors. Logos, incidental text, and inactive controls have specific exceptions in WCAG.

Large text is at least 18 point, roughly 24 CSS pixels, at regular weight or at least 14 point, roughly 18.5 CSS pixels, in bold. Thin or unusual typefaces can still be difficult to read, so aiming above the minimum is safer.

Browsers smooth letter edges by blending text and background colors. An edge pixel therefore has less contrast than the solid source color. The center of a thick stroke is more likely to represent the intended text color, while the background sample should come from a nearby flat area.

No. This checker measures one foreground and background pair. A complete review also covers semantics, keyboard access, focus visibility, zoom, motion, component states, images, and information conveyed by color alone. Gradients and changing backgrounds may require checks at multiple points.