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WCAG Contrast & Palette Checker

Calculate WCAG 2.1 relative luminance and evaluate AA/AAA accessibility compliance. Client-side processing executed directly in browser memory.

Instant Local Processing
In-Memory Client Runtime
Lossless Quality Export
7.8:1
AAAAA
WCAG 2.1 AAA
Luminance Ratio
Normal and large text safe
100% In-Browser RAM | WCAG 2.1 & APCA Contrast Engine

WCAG Contrast & Color Studio

Dual-engine contrast auditing (WCAG 2.1 & APCA), real-time typography simulation, 1-click color auto-fix, and colorblind vision preview.

Presets:
RGB: 21, 21, 21
HSL: 0°, 0%, 8%
Lightness Adjustment:8%
RGB: 250, 248, 240
HSL: 48°, 50%, 96%
Lightness Adjustment:96%
WCAG 2.1 Relative Luminance
AAA Pass (Enhanced)
17.17: 1

Relative luminance contrast based on ISO/IEC 17025 standard calibration formulas.

APCA Lightness Contrast (WCAG 3)
Dark on Light (BoW)
Lc +93.4
Fluent body text (all sizes & weights)

APCA models human spatial perception, accounting for text size, font weight, and polarity adaptation.

Smart Color Auto-Optimizer

Calculates and shifts lightness along the HSL color vector to the nearest compliant threshold.

Target:
Live Interactive UI & Typography Simulation
Design System Preview

Accessible Interfaces For Everyone

Ratio: 17.17:1
Small Body Text (14px regular)PASS AA

The quick brown fox jumps over the lazy dog. Legible typographic scale ensures clarity across content hierarchies, regardless of device display specs.

Threshold: 4.5:1•Current: 17.17:1
Large Text (18px bold / 24px)PASS AA

Bold visual statements require minimum 3.0:1 contrast for universal readability.

Threshold: 3.0:1•Current: 17.17:1
Graphical Objects & UI Components (SC 1.4.11)PASS (3.0:1)
Text Input:
Placeholder value...
Solid Button:
Outline Button:
WCAG 2.1 Full Compliance Audit Matrix
WCAG AA Normal
Threshold: 4.5:1
WCAG AA Large
Threshold: 3.0:1
WCAG AAA Normal
Threshold: 7.0:1
UI Non-Text (1.4.11)
Threshold: 3.0:1
Colorblind Simulation Studio (Brettel/Machado Model)

Simulates retinal cone deficiencies to guarantee readability across all color vision spectra.

Protanopia17.27:1
Red-blind (L-cone absent)
~1% of males
Sample Text Aa
FG: #151515BG: #F9F9F2
Deuteranopia17.27:1
Green-blind (M-cone absent)
~6% of males
Sample Text Aa
FG: #151515BG: #F9F9F2
Tritanopia16.79:1
Blue-blind (S-cone absent)
~0.01% of population
Sample Text Aa
FG: #151515BG: #FAF4F4
Achromatopsia17.19:1
Monochromacy (complete color blindness)
~0.003% of population
Sample Text Aa
FG: #151515BG: #F8F8F8
Three Simple Steps

How to use WCAG Contrast & Palette Checker

Direct execution in browser memory with full vector precision.

1

Upload or Drop File

Select your source file from your local disk or drag and drop it into the workspace canvas.

100% Private in RAM
2

Process & Refine

Review automated results and use interactive controls like brush, crop handles, or sliders for precision adjustment.

Real-Time Preview
3

Download Clean Output

Export your high-resolution file directly to local disk with full resolution integrity.

Lossless Direct Export
Engineering

Built for privacy, speed, and precision

Ephemeral In-Memory Runtime

Files are processed ephemerally inside client-side RAM or temporary stateless workers. No storage, no logs.

Sub-Second Processing

Optimized canvas transformations and vector operations execute directly on the client thread without network transit.

Hardware Accelerated

Takes full advantage of modern GPU WebGL and HTML5 Canvas pipelines for fluid 60fps brush and pan interactions.

FAQ

Frequently Asked Questions

Everything you need to know about WCAG Contrast & Palette Checker

Yes, WCAG Contrast & Palette Checker is 100% free with no monthly subscription, no credit card requirement, and no hidden limits. You can process as many files as you need.

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