A color contrast checker that turns "is this text too faint to read on that background?" into a number you can trust. Enter a foreground (text) color and a background color as HEX like `#1e293b`, and it computes the contrast ratio (e.g. `4.5:1`) using the WCAG 2.x relative-luminance formula, then shows at a glance — with pass/fail chips — whether the pair meets the AA and AAA accessibility levels for both normal and large text. The thresholds are 4.5:1 (AA) and 7:1 (AAA) for normal text, and 3:1 (AA) and 4.5:1 (AAA) for large text (over 18pt ≈ 24px, or over 14pt bold); UI components and graphical objects generally need 3:1 (AA). Besides typing HEX, you can pick a color visually with the swatch picker next to each field and the box fills in reverse; three-digit shorthand like `#fff` is accepted too. A "Swap" button flips the foreground and background in one click so you can compare a light-on-dark and dark-on-light arrangement instantly. The two colors are applied to real sample text (normal and large) in a live preview, so you can judge readability with your eyes, not just the numbers. Your chosen pair is saved in your browser so the next visit starts from the same palette. Importantly, the color values you enter are never uploaded, stored, or sent to a server — all calculation happens with JavaScript entirely inside your browser, so unreleased brand colors and in-progress palettes stay on your device. Note that this tool focuses on the contrast (luminance) ratio only: it does not simulate color-vision deficiency, nor does it sample text over image or gradient backgrounds. For semi-transparent colors, convert them to the opaque blended color before entering.