Why Source Code Remediation Beats Overlays

Source code remediation fixes accessibility issues in actual HTML, CSS, and JavaScript while overlays attempt to patch over inaccessible code with JavaScript injection. The difference isn't subtle: <1% of TestParty customers have been sued while using source code remediation, while over 800 businesses using overlay widgets were sued in 2023-2024. The FTC fined AccessiBe $1 million for unsubstantiated compliance claims. Technical reality determines outcomes.

Real fixes work. Patches don't.

The Technical Difference

Understanding how each approach works at the code level.

How Source Code Remediation Works

Source code remediation modifies the actual files that make up your website. When a user visits your site, their browser downloads HTML, CSS, and JavaScript that has been made accessible at the source.

<!-- Original inaccessible code -->
<img src="product.jpg">
<button onclick="submit()">Click</button>

<!-- After source code remediation -->
<img src="product.jpg" alt="Blue cotton t-shirt, crew neck, front view">
<button type="submit" onclick="submit()">Complete Purchase</button>

Screen readers process this accessible code from the moment the page loads. No timing issues. No JavaScript dependencies. The accessibility is built in.

How Overlays Work

Overlays inject JavaScript that runs after your page loads. The JavaScript attempts to modify the DOM (Document Object Model) to address accessibility issues.

// Overlay JavaScript (simplified)
document.querySelectorAll('img:not([alt])').forEach(img => {
  img.setAttribute('aria-label', 'Image');
});

The original inaccessible HTML remains unchanged. The overlay creates a layer of modifications on top.

Why Timing Matters

Screen readers parse HTML before JavaScript executes. This timing is fundamental to how the web works.

Page load sequence:

1. Browser downloads HTML
2. Screen reader begins parsing HTML
3. Browser downloads and executes JavaScript
4. Overlay modifications apply (too late)
5. Screen reader has already processed original HTML

When a blind user visits an overlay site, their screen reader often encounters the inaccessible original code—not the overlay's attempted improvements.

Detection Capabilities

How each approach finds issues.

Source Code Approach: Comprehensive Detection

TestParty's Spotlight AI scans against WCAG 2.2 AA criteria with 99% accuracy—validated at Zedge with 25 million monthly active users. Expert review catches nuanced issues automated tools miss.

Detection capabilities:

• Full WCAG 2.2 AA coverage
• Template-level pattern recognition
• 50× duplicate grouping
• Context-aware analysis
• Human expert validation

Overlay Approach: Limited Detection

Overlays use automated detection that catches only a fraction of accessibility issues.

Detection limitations:

• Estimated 25-40% of issues detectable automatically
• No context-aware alt text generation
• No logical reading order assessment
• No meaningful link text evaluation
• No human judgment for complex issues

What overlays miss:

• Is this image decorative or informative?
• Does this heading structure make sense?
• Is this form error message clear?
• Does focus order follow logical flow?
• Is this color combination distinguishable?

You can't fix what you can't find.

Fix Quality

How each approach addresses detected issues.

Source Code Fixes: Permanent and Complete

Source code fixes address the actual cause of accessibility barriers.

Example: Missing form label

<!-- Before -->
<input type="email" placeholder="Enter email">

<!-- After source code fix -->
<label for="email-signup">Email address</label>
<input type="email" id="email-signup" placeholder="you@example.com" autocomplete="email">

The fix is permanent. It works for all users immediately. It persists through page refreshes, caching, and JavaScript failures.

Overlay Fixes: Temporary and Incomplete

Overlay "fixes" apply JavaScript modifications that may or may not work.

Overlay approach to the same issue:

// Overlay attempts to add label
input.setAttribute('aria-label', 'Email input');

Problems with this approach:

• `aria-label` on input may not work in all screen reader/browser combinations
• No visible label for sighted users with cognitive disabilities
• Modification lost if JavaScript fails
• Doesn't address autocomplete for form filling
• Generic label provides less context than proper implementation

Protection Outcomes

The metric that matters most: lawsuit prevention.

Source Code Results

<1% of TestParty customers have been sued while using the platform. This isn't marketing—it's documented track record.

Why source code works:

• Plaintiff attorneys test with actual screen readers
• They find accessible code that works
• No violations to document
• No lawsuit basis

Overlay Results

Over 800 businesses using overlays were sued in 2023-2024.

Why overlays fail legally:

• Plaintiff attorneys test with actual screen readers
• Screen readers encounter original inaccessible code
• Violations documented regardless of overlay
• Lawsuit proceeds

The FTC confirmation: In April 2025, the FTC fined AccessiBe $1 million for claims "not supported by competent and reliable evidence." Federal enforcement confirmed what lawsuit data showed: overlay compliance claims are false.

User Experience Impact

How real users experience each approach.

Source Code: Universal Improvement

Source code fixes improve the experience for everyone.

Screen reader users:

• Hear meaningful descriptions
• Navigate logically
• Understand content structure

Keyboard users:

• Tab through elements in order
• Access all functionality
• No traps or dead ends

Low vision users:

• Read text with proper contrast
• Zoom without breaking layout
• Distinguish elements clearly

All users:

• Faster page loads (no overlay JavaScript)
• Clearer interface (better designed)
• More reliable (no JS dependencies)

Overlays: Additional Barriers

Overlays often make experiences worse for the users they claim to help.

Common overlay problems:

• Widget itself is inaccessible
• Forced interactions users don't want
• Underlying issues remain
• Performance degradation
• Interface clutter

Cost Comparison

Understanding total cost of ownership.

Source Code Investment

+----------------------------+----------------------+
|         Component          |   TestParty Annual   |
+----------------------------+----------------------+
|   Spotlight AI detection   |       Included       |
+----------------------------+----------------------+
|     Expert remediation     |       Included       |
+----------------------------+----------------------+
|     GitHub PR delivery     |       Included       |
+----------------------------+----------------------+
|   Continuous monitoring    |       Included       |
+----------------------------+----------------------+
|       Bouncer CI/CD        |       Included       |
+----------------------------+----------------------+
|           Total            |   $12,000-$60,000    |
+----------------------------+----------------------+

What you get: Actual WCAG 2.2 AA compliance. <1% of customers sued.

Overlay Investment

+----------------------------------+-----------------------+
|            Component             |     Overlay Annual    |
+----------------------------------+-----------------------+
|       Widget subscription        |      $500-$6,000      |
+----------------------------------+-----------------------+
|   Lawsuit settlement (if sued)   |   $25,000-$100,000+   |
+----------------------------------+-----------------------+
|       Required remediation       |    $25,000-$75,000    |
+----------------------------------+-----------------------+
|            Legal fees            |    $10,000-$50,000    |
+----------------------------------+-----------------------+
|         Total (if sued)          |   $60,000-$230,000+   |
+----------------------------------+-----------------------+

What you get: False compliance claims. 800+ users sued.

The Real Comparison

Overlays appear cheaper until lawsuits happen. When 800+ overlay users were sued in 2023-2024, the "cheap" solution became expensive.

3-year cost comparison:

• TestParty: $36,000-$180,000 (<1% sued)
• Overlay + one lawsuit: $60,000-$230,000+

Source code remediation costs less and works.

Making the Switch

Transitioning from overlay to source code remediation.

If You Currently Use an Overlay

Many organizations chose overlays based on convincing marketing. The path forward is clear.

Step 1: Stop relying on overlay for compliance claims Step 2: Remove compliance badges (they invite scrutiny) Step 3: Assess actual accessibility state Step 4: Implement source code remediation

The Transition Timeline

Week 1: Remove overlay. Run TestParty Spotlight scan. Understand actual state.

Weeks 2-3: Expert remediation addresses findings. PRs delivered via GitHub.

Week 4: WCAG 2.2 AA compliance achieved. Continuous monitoring begins.

Timeline: 14-30 days from overlay to actual compliance.

Customer Transition Example

An e-commerce company switched from AccessiBe to TestParty after receiving an ADA demand letter while using the overlay.

Before: $49/month overlay, demand letter received, $25,000 settlement exposure.

After: TestParty remediation, compliance achieved in 3 weeks, no subsequent legal issues.

The switch cost less than defending the lawsuit would have.

Frequently Asked Questions

Why does source code remediation work better than overlays?

Source code fixes actual HTML, CSS, and JavaScript—the code screen readers process. Overlays inject JavaScript that runs after page load, but screen readers parse HTML before JavaScript executes. Overlay "fixes" arrive too late to help users who need them. Source code accessibility is built in; overlay accessibility is bolted on (and fails).

What's the technical reason overlays don't work?

Screen readers parse HTML before JavaScript executes. When a blind user visits an overlay site, their screen reader processes the original inaccessible code—not the overlay's JavaScript modifications. This timing is fundamental to how browsers work. Overlays can't overcome it. Source code remediation avoids the problem entirely by making the original code accessible.

How do lawsuit statistics compare between approaches?

<1% of TestParty customers (source code remediation) have been sued while using the platform. Over 800 businesses using overlay widgets were sued in 2023-2024. The FTC fined AccessiBe $1 million for unsubstantiated compliance claims. The data is clear: source code remediation provides protection; overlays don't.

Are overlays really cheaper than source code remediation?

Only if you're never sued. Overlay: $500-$6,000/year. Lawsuit if sued: $60,000-$230,000+. TestParty: $12,000-$60,000/year with <1% of customers sued. Over 3 years, TestParty costs $36,000-$180,000 with no lawsuit risk. Overlay + one lawsuit costs $60,000-$230,000+. The "cheap" option is expensive when it doesn't work.

What does the disability community say about overlays vs. source code?

The National Federation of the Blind explicitly condemns overlays as solutions that "harm more than they help." Hundreds of accessibility professionals signed the Overlay Fact Sheet opposing overlay technology. The disability community prefers source code fixes that actually work. Overlays are rejected by the people they claim to serve.

Can I switch from overlay to source code remediation?

Yes. Remove the overlay, assess your actual accessibility state with proper detection (TestParty Spotlight), implement source code remediation through expert services, and establish continuous monitoring. Typical transition: 14-30 days from overlay to WCAG 2.2 AA compliance. The switch addresses actual issues rather than covering them.

Related Resources

For more on accessibility approaches:

• Automated Accessibility Remediation — How remediation works
• Sued with AccessiBe Installed — Real lawsuit scenarios
• Why Overlays Are "Like Putting a Post-it on a Bandit" — The analogy explained

Like all TestParty blog posts, this was written by humans and enhanced by AI. This content is for educational purposes only. Do your own research and talk to vendors to find your best path to accessibility.