{"$schema":"https://toolsly.tools/schemas/tool-manifest-v1.json","generated":"2026-05-20T20:47:38.304Z","discovery":{"catalog":"https://toolsly.tools/tools.json","llmsTxt":"https://toolsly.tools/llms.txt","sitemap":"https://toolsly.tools/sitemap.xml"},"relatedTools":[{"slug":"color-converter","name":"Color Converter","url":"https://toolsly.tools/color-converter"},{"slug":"complementary-color","name":"Complementary Color Generator","url":"https://toolsly.tools/complementary-color"},{"slug":"triadic-colors","name":"Triadic Colors Generator","url":"https://toolsly.tools/triadic-colors"},{"slug":"analogous-colors","name":"Analogous Colors Generator","url":"https://toolsly.tools/analogous-colors"},{"slug":"shade-tint-generator","name":"Shade & Tint Generator","url":"https://toolsly.tools/shade-tint-generator"},{"slug":"random-color","name":"Random Color Generator","url":"https://toolsly.tools/random-color"},{"slug":"gradient-generator","name":"CSS Gradient Generator","url":"https://toolsly.tools/gradient-generator"},{"slug":"color-name-finder","name":"Color Name Finder","url":"https://toolsly.tools/color-name-finder"}],"kind":"utility","slug":"wcag-contrast-checker","name":"WCAG Contrast Checker","description":"Check WCAG 2.1 contrast ratio for any foreground/background pair — AA & AAA, normal & large text.","longDescription":"Calculate the contrast ratio between a foreground and a background color using the official WCAG 2.1 luminance formula. The tool reports the ratio (e.g. \"4.52:1\") and pass/fail status for all four conformance levels: AA Normal (≥4.5:1), AA Large (≥3:1), AAA Normal (≥7:1), and AAA Large (≥4.5:1). Use this to verify body text, headings, button labels, and link colors meet accessibility minimums. Algorithm: linearize each sRGB channel via the gamma curve, weight as 0.2126·R + 0.7152·G + 0.0722·B for relative luminance, then compute (Llight + 0.05) / (Ldark + 0.05). All math runs in your browser.","category":"color","categoryName":"Color","keywords":["wcag contrast checker","wcag contrast ratio","wcag contrast online","accessibility contrast","color contrast checker","a11y contrast tool","aa contrast check","aaa contrast check","text contrast ratio","wcag 2.1 contrast","contrast ratio calculator","wcag color checker free"],"badge":"Audit","url":"https://toolsly.tools/wcag-contrast-checker","inputs":[{"type":"text","key":"fg","label":"Foreground color","placeholder":"#111827","defaultValue":"#111827","monospace":true,"help":"Text or icon color."},{"type":"text","key":"bg","label":"Background color","placeholder":"#ffffff","defaultValue":"#ffffff","monospace":true}],"outputs":[{"key":"ratio","label":"Contrast ratio"},{"key":"aaNormal","label":"AA Normal (≥4.5:1)"},{"key":"aaLarge","label":"AA Large (≥3:1)"},{"key":"aaaNormal","label":"AAA Normal (≥7:1)"},{"key":"aaaLarge","label":"AAA Large (≥4.5:1)"},{"key":"luminance","label":"Relative luminance (fg / bg)"},{"key":"preview","label":"Sample","multiline":true}],"invocation":{"webUi":"https://toolsly.tools/wcag-contrast-checker","api":null,"notes":"Currently invoked via the web UI at `webUi`. Inputs are form fields; outputs are structured text values. A remote MCP/REST API is planned."}}