Rule ID: ace-img-no-server-map

Flag server-side image maps which cannot provide text alternatives for clickable regions

WCAG 2.0 (A) - WCAG 2.2 (A) 2.1.1: Keyboard Blind Deafblind Mobility Legal Risk

What This Rule Checks

For users who rely on screen readers or other assistive technologies, server-side image maps can pose significant accessibility challenges. Server-side image maps are managed by the server rather than the browser, meaning clickable areas are not easily interpreted by assistive technologies. This results in users being unable to interact with or understand the purpose of the clickable regions.

Who Is Affected

This issue primarily affects: Blind users, who rely entirely on screen readers or braille displays to navigate and interact with content; Deafblind users, who rely on braille displays and cannot access visual or auditory content; Mobility users, who navigate using keyboards, switches, voice control, or other assistive input devices.

Why This Matters

Server-side image maps transmit click coordinates to the server, making it impossible to provide text alternatives for individual clickable regions. Keyboard users cannot target specific areas. This violates WCAG 1.1.1.

How to Fix

To make image maps accessible, replace server-side image maps with client-side image maps. Client-side image maps allow each clickable area to have descriptive alt text and can be more easily interpreted by screen readers.

Code Examples

Incorrect Markup Solutions:

Code example

<!-- Server-side image map (inaccessible) -->
<a href="/map-handler">
  <img
    src="map.png"
    ismap
    alt="Site map">
</a>

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Correct Markup Solutions:

Code example

<!-- Client-side image map with labeled areas -->
<img
  src="map.png"
  usemap="#sitemap"
  alt="Site navigation map">

<map name="sitemap">
  <area
    shape="rect"
    coords="0,0,100,50"
    href="/about"
    alt="About us">

  <area
    shape="rect"
    coords="100,0,200,50"
    href="/products"
    alt="Products">
</map>

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Common Mistakes to Avoid

Using ismap attribute which relies on mouse coordinates for navigation.
Not providing a text-based alternative navigation for image map content.
Assuming server-side image maps can be made accessible with alt text alone.

Tip: When writing alt text, describe the image’s function and meaning, not just its appearance. For complex images like charts, provide a brief alt attribute and a longer description in surrounding text or a linked resource.

Related WCAG Criteria

2.1.1: Keyboard