Digital Accessibility: How to Test Your Site with Free Tools and Fix Critical Errors

Too many sites remain non-compliant with good accessibility practice. This practical guide offers a prioritised checklist of critical errors to be corrected, a 30-minute testing method, and an overview of free tools (WAVE, Lighthouse, DevTools axis, Accessibility Insights, contrast analysers, screen readers) to identify concrete problems: insufficient contrasts, disordered titles, faulty keyboard navigation, inaccessible forms, media without alternatives. You'll find examples, error message templates, advice on legible page layout (mobile first) and a 30-60-90 day roadmap to anchor accessibility in your publishing habits. The aim: to make your site understandable, navigable and usable by everyone - without extra cost or gasworks.

Introduction

Digital accessibility aims to ensure that all people - including those with disabilities, senior citizens, users of technical aids or slow connections - can consult and use a website. Beyond the obligations (inspired by the international WCAG recommendations and, in France, the RGAA guidelines), it's a question of common sense: a clear, readable and navigable site converts better, costs less to maintain and inspires more trust.

The good news: 80% of irritants can be corrected with simple gestures (contrasts, font sizes, title structure, keyboard support, form labels, alternative image texts). This tutorial cuts to the chase: what to test, with which free tools, and how to quickly fix what matters.

1) Why accessibility is a priority in 2025

A few concrete reasons to place accessibility among your operational priorities :

• Real audience: a significant proportion of internet users have specific needs (vision, motor skills, cognition) - and we all sometimes have our hands clutched, the screen small, the light bright.
• Mobile first: on a small screen, legibility and navigation become critical (font sizes, contrasts, clickable areas, focus).
• SEO & conversions: structured content, coherent headlines, text alternatives and performance positively influence findability and engagement.
• Brand & trust: an inclusive site reflects a caring organisation - it's a strong signal to users, partners and recruiters.

2) The most frequent critical errors (and their impact)

Start with these issues: they degrade the experience the most and are often simple to fix.

3) The best free tools (and when to use them)

No one tool covers everything. Combine several approaches for a reliable diagnosis.

4) "30 minute" test method (express lane)

When you're short on time, it's better to have a small, well-targeted audit than a big one that never ends. Here's a flow that fits into half an hour:

1. Choose 3 representative pages: Home, a content page (article/product), a form.
2. Lighthouse (5 min): "Accessibility" tab to detect major gaps (titles, alt, labels).
3. WAVE (10 min): go through each page, note the red errors (contrast, structure), then the alerts.
4. Keyboard (5 min): Tab, Enter, Escape Check visible focus, logical order, modal output.
5. Contrast (5 min): two or three weak areas (text on image background, secondary buttons, mentions).
6. Screen reader (5 min): a quick tour (headers, links, form) to catch inconsistencies.

Result: a list of concrete actions ranked "to correct right away" vs "to plan" - that's enough to get the ball rolling.

5) Contrast & colour: legibility first

Aim for a contrast ratio of at least AA (4.5:1 for normal text, 3:1 for large text). Don't forget the states (hover, focus, disabled) and text on images.

Quick gestures

• Enhance text slightly (#0a0a0a instead of light grey).
• Lighten backgrounds behind text, or add a semi-opaque overlay.
• Avoid "transparent" buttons on complex visuals.
• Do not differentiate by colour alone (add icon/text).

    Copy code
    
/* Palette readable and focus visible */
:root{
  --text:#1d1d1f; --bg:#fff;
  --primary:#0a53b5; --primary-contrast:#fff;
  --focus:#ffbf47;
}
body{color:var(--text);background:var(--bg);font-size:18px;line-height:1.6;}
a, .btn-primary{background:var(--primary);color:var(--primary-contrast);}
:focus{outline:3px solid var(--focus);outline-offset:2px;}
    
  

6) Headings, structure & markers: giving useful tags

Headings allow everyone (and screen readers) to get to the point. A single H1 per page; then H2 for main sections, H3 for sub-sections. Avoid empty headings (" ") and headings used for visual formatting only.

Example of a healthy structure

    Copy code
    
<main id="content">
  <h1>Main title of the page</h1>
  <h2>Section 1</h2>
  <p>...</p>
  <h3>Subsection 1.1</h3>
  <p>...</p>
  <h2>Section 2</h2>
  <p>...</p>
</main>
    
  

Add a pass link ("Go to content") at the top of the page to jump directly to the main content via the keyboard.

7) Keyboard, focus & components: making interaction universal

We need to be able to do everything with the keyboard: open a menu, activate a button, close a modal, navigate a carousel. The focus must be visible, particularly on custom elements (styled buttons, transformed links).

Control points

• Logical tab order (top to bottom, left to right).
• Focus always visible (bright colour, thick outline, not just a light shadow).
• Focus traps prohibited (modal that prevents returning without Escape/close).
• Dynamic components (accordions, tabs) accessible via standard keys.

    Copy code
    
/* Highly visible focus, even on custom elements */
:focus{outline:3px solid #ffbf47; outline-offset:2px;}
button:focus, [role="button"]:focus, a:focus{box-shadow:0 0 0 3px rgba(255,191,71,.45);}
    
  

8) Forms: labels, helpers and error messages

Forms concentrate most of the frustration. Three winning rules: a label for each field, help (examples, constraints) linked to the field, and clear error messages (in the right place, readable by screen readers).

Simple and robust template

    Copy code
    
<form novalidate>
  <label for="email">Your email</label>
  <input id="email" name="email" type="email" aria-describedby="help-email error-email">
  <small id="help-email">Ex. nom@domaine.tld</small>
  <div id="error-email" class="error" role="alert"></div>
  <button type="submit">Send</button>
</form>
    
  

Display the error as close to the field as possible, link it via aria-describedby, use simple language ("Email address is required" rather than "Invalid field").

9) Images, videos and documents: useful alternatives

The media must transmit information to everyone, even without sight, sound, or on a weak network.

Images

• Relevant Alt: describe the information, not the aesthetics ("Photo of the mayor signing the charter").
• Decorative images: alt="" (empty), to be ignored by screen readers.
• Avoid text in the image (or provide text in the page).

Video & audio

• Synchronised subtitles + transcript (useful for research and translation).
• Accessible player (keyboard controls, visible focus).

PDF & documents

• Prefer a web page when possible (more accessible, responsive, findable).
• If PDF: tagged, titles, reading order, actual text (no scanned images).

10) 30-60-90 day roadmap & governance

To install lasting reflexes, structure your effort in three stages:

Days 1-30 - Quick wins

• Express review (3 pages) + corrections to contrast, titles, focus, alt.
• Page templates (H1/H2/H3 titles), accessible form patterns.
• Edit checklist pasted into your CMS.

Days 31-60 - Components & media

• Menus, tabs, modals: adopting accessible components.
• Videos: subtitles/transcripts; priority PDFs: HTML versions.
• Internal documentation: "how to write an alt", "how to name a link".

Days 61-90 - Process & follow-up

• Integrate a "keyboard + WAVE" test into each upload.
• Measure 3 indicators: Lighthouse score, critical WAVE errors, average correction time.
• Train the team (2 h) and appoint an accessibility referent.

If you need a one-off boost (flash audit, component kit, short training course), targeted support can save you weeks. The idea: make you autonomous with templates and a simple method.

Points to remember

Conclusion

Accessibility isn't a one-off project: it's a habit. By correcting the most visible errors, testing regularly with simple tools and adopting robust patterns, you'll make your site more welcoming, more efficient - and more effective. This work benefits everyone: people with disabilities, senior citizens, mobile users in a hurry... and your organisation.

Start small, get to the essentials, and make your pages really usable. Results (engagement, trust, conversions) quickly follow when the experience improves.

Appendix

"Before publication" checklist (to paste into your CMS)

• A single H1, hierarchical headings (H2 → H3).
• Contrast AA on text and buttons (and their states).
• Keyboard navigation OK, focus clearly visible.
• Each image has a relevant alt (or empty if decorative).
• Form: linked labels, helpers, explicit errors.
• Videos: subtitles; PDF: HTML version if possible.
• Explicit links (avoid "click here").
• Quick test Lighthouse + WAVE + keyboard.

Complementary Resources

• Digital accessibility (FR) - RGAA portal
• W3C WAI - WCAG (international recommendations)
• WAVE - rapid online evaluation
• Lighthouse - accessibility audit & performance
• axe DevTools - browser extension
• Accessibility Insights for Web - FastPass
• Color Contrast Analyser - TPGi
• NVDA - free screen reader (Windows)
• Guides and tutorials (performance, SEO, accessibility)