Accessibility Testing

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The Screenshot API includes powerful accessibility testing features that allow you to simulate how web pages appear to users with various vision deficiencies. This enables compliance testing for WCAG, ADA, Section 508, and other accessibility standards.

Why Accessibility Matters: Over 1 billion people worldwide live with some form of visual impairment. Color blindness alone affects approximately 8% of males and 0.5% of females. Testing your website's accessibility is not just good practice-it's often a legal requirement.

Vision Deficiency Simulation

Use the vision_deficiency parameter to capture screenshots that simulate how your web pages appear to users with specific visual impairments:

https://api.scrapfly.io/screenshot?url=https%3A%2F%2Fweb-scraping.dev%2Fproduct%2F1&vision_deficiency=deuteranopia&key=

Supported Vision Deficiency Types

Type	Description	Prevalence	Common Issues Revealed
`none`	Normal vision (default)	-	-
`deuteranopia`	Red-green color blindness (green-blind) Difficulty distinguishing green from red; green appears beige/gray	~6% of males	Red/green status indicators Success/error color coding Traffic light metaphors
`protanopia`	Red-green color blindness (red-blind) Reduced sensitivity to red light; red appears dark/black	~2% of males	Red warning messages Red call-to-action buttons Price/discount highlighting
`tritanopia`	Blue-yellow color blindness Difficulty distinguishing blue from yellow and violet from red	~0.01%	Blue hyperlinks on light backgrounds Yellow warning indicators Sky/water imagery contrast
`achromatopsia`	Complete color blindness (monochromacy) Complete inability to perceive color; sees only in grayscale	~0.003%	Color-only information Insufficient contrast ratios Charts/graphs without patterns
`blurredVision`	Blurred/unfocused vision Simulates uncorrected refractive errors or age-related vision loss	~2.2B globally	Small text readability Low contrast elements Icon-only navigation

Code Examples

Python

import requests

# Test how page appears to users with deuteranopia (red-green color blindness)
response = requests.get(
    "https://api.scrapfly.io/screenshot",
    params={
        "key": "YOUR_API_KEY",
        "url": "https://example.com",
        "vision_deficiency": "deuteranopia",
        "capture": "fullpage"
    }
)

# Save the accessibility test screenshot
with open("accessibility_test_deuteranopia.jpg", "wb") as f:
    f.write(response.content)

Python SDK

from scrapfly import ScrapflyClient, ScreenshotConfig

client = ScrapflyClient(key="YOUR_API_KEY")

# Test all vision deficiency types
vision_types = ["deuteranopia", "protanopia", "tritanopia", "achromatopsia", "blurredVision"]

for vision_type in vision_types:
    result = client.screenshot(ScreenshotConfig(
        url="https://example.com",
        vision_deficiency=vision_type,
        capture="fullpage"
    ))
    result.save(f"accessibility_{vision_type}.jpg")
    print(f"Saved screenshot for {vision_type}")

TypeScript SDK

import { ScrapflyClient, ScreenshotConfig } from 'scrapfly-sdk';

const client = new ScrapflyClient({ key: 'YOUR_API_KEY' });

// Test for color blindness accessibility
const result = await client.screenshot(new ScreenshotConfig({
    url: 'https://example.com',
    visionDeficiency: 'deuteranopia',
    capture: 'fullpage'
}));

// Save the result
await result.save('accessibility_test.jpg');

cURL

# Test for protanopia (red-blind)
curl -G \
    --url "https://api.scrapfly.io/screenshot" \
    --data-urlencode "key=YOUR_API_KEY" \
    --data-urlencode "url=https://example.com" \
    --data-urlencode "vision_deficiency=protanopia" \
    --data-urlencode "capture=fullpage" \
    -o accessibility_protanopia.jpg

# Test for blurred vision
curl -G \
    --url "https://api.scrapfly.io/screenshot" \
    --data-urlencode "key=YOUR_API_KEY" \
    --data-urlencode "url=https://example.com" \
    --data-urlencode "vision_deficiency=blurredVision" \
    --data-urlencode "capture=fullpage" \
    -o accessibility_blurred.jpg

Compliance Standards

Vision deficiency simulation helps you test compliance with major accessibility standards and regulations:

WCAG 2.2 (ISO/IEC 40500:2025)

Web Content Accessibility Guidelines require that information conveyed by color differences is also available without color (Success Criterion 1.4.1).

1.4.1 Use of Color - Color not sole visual means
1.4.3 Contrast (Minimum) - 4.5:1 text contrast
1.4.11 Non-text Contrast - 3:1 for UI components

Section 508 (US Federal)

US federal agencies must ensure electronic content is accessible to people with disabilities, including those with color vision deficiencies.

Required for federal contractors
Applies to public-facing websites
Aligns with WCAG 2.0 Level AA

ADA Title III

The Americans with Disabilities Act requires places of public accommodation to be accessible, which courts have interpreted to include websites.

Applies to commercial websites
Subject to DOJ enforcement
Private lawsuit exposure

European Accessibility Act (EAA)

EU directive requiring digital products and services to be accessible, with enforcement beginning in 2025.

Covers e-commerce, banking, transport
Applies to EU market participants
Enforcement from June 2025

Best Practices

Accessibility Testing Workflow

Test all color blindness types: Run your pages through all vision deficiency simulations, not just the most common ones. Issues may appear only in specific types.
Focus on interactive elements: Pay special attention to buttons, links, form validation, and status messages that use color to convey meaning.
Test error states: Ensure error messages and validation feedback are visible without relying on red/green color coding.
Verify data visualizations: Charts, graphs, and maps often rely heavily on color. Test with achromatopsia to see if information is still distinguishable.
Check text legibility: Use blurredVision to identify text that may be too small or have insufficient contrast.

Use Cases

QA Testing

Integrate accessibility screenshots into your CI/CD pipeline for automated visual regression testing across all vision types.

Compliance Audits

Generate evidence for accessibility audits by capturing screenshots that demonstrate WCAG/ADA compliance or identify issues.

Design Validation

Validate design mockups and color palettes before development to ensure accessibility is built in from the start.

Combining with Other Features

Vision deficiency simulation works seamlessly with other Screenshot API features:

capture=fullpage - Capture the entire scrollable page with vision deficiency simulation
options=dark_mode - Test dark mode themes for accessibility
resolution=375x812 - Test mobile responsiveness alongside accessibility
cache=true - Cache results when running multiple tests on the same page

# Full accessibility audit: fullpage + dark mode + deuteranopia
curl -G \
    --url "https://api.scrapfly.io/screenshot" \
    --data-urlencode "key=YOUR_API_KEY" \
    --data-urlencode "url=https://example.com" \
    --data-urlencode "vision_deficiency=deuteranopia" \
    --data-urlencode "options=dark_mode" \
    --data-urlencode "capture=fullpage" \
    -o dark_mode_accessibility.jpg

Billing

Vision deficiency simulation is included at no additional cost. It's a rendering flag similar to dark_mode or print_media_format and doesn't affect your API credit usage.

Screenshot API Getting Started - Full API reference
Screenshot API Billing - Credit costs and spending management
Screenshot API Player - Interactive testing tool