Accessibility Testing Tools

A collection of recommended browser extensions, bookmarklets, and software to facilitate conformance testing with the Minimum Digital Accessibility Standards (MDAS).

To use, drag the links below to the bookmarks bar or right-click and save as bookmark.

ANDI Accessibility Testing Tool

ANDI (Accessible Name & Description Inspector) is an accessibility testing tool developed by the U.S. Social Security Administration. The tool assists with performing full manual evaluations. One notable feature is it reveals the expected output of a screen reader on interactive elements.

Bookmarklet: ANDI

Text Spacing

Perform a quick test of WCAG 2.1 Success Criterion 1.4.12 Text Spacing by applying the specified styles to the current page.

Bookmarklet: Text Spacing Test

The original version of this tool was created by Steve Faulkner with assistance from Patrick H. Lauke.


Opens the current page in a new window at 1280×1024 pixels to allow testing of WCAG 2.1 Success Criterion 1.4.10 Reflow. After opening the new window, increase the browser zoom level to 400%.

Bookmarklet: Zoom Test

Duplicate IDs (WCAG 2.1 SC 4.1.1)

Important note: WCAG 2.1 has been updated to state that this Success Criterion (4.1.1) should be considered as always satisfied for any content using HTML or XML. The current recommendation of the DAC is to follow this guidance except for cases of duplicate IDs, which, while they do not always cause barriers, they have a high probability of doing so and may be missed when testing other success criteria. The process of testing for duplicate IDs is as follows:

Step 1: Send the serialized DOM of the current page to the W3C HTML validation service. Use with the parsing bookmarklet below.

Bookmarklet: Check serialized DOM of current page

Step 2: Show only duplicate IDs in the W3C HTML validation service and where they first appear. Use this bookmarklet on the W3C result page after running the serialized DOM check above. (Experimental)

Bookmarklet: Duplicate IDs


Use this bookmarklet to evaluate document conformance requirements for use of ARIA attributes in HTML and allowed ARIA roles, states, and properties. Created and maintained by The Paciello Group

Bookmarklet: WAI-ARIA Usage

Autocomplete Attribute

This bookmarklet will display the value of the `autocomplete` attribute on input elements. Use this to evaluate for conformance with WCAG 1.3.5 Identify Input Purpose, along with the WCAG 2.1 list of Input Purposes for User Interface Components. Inputs that need to have this attribute set include, but are not limited to, First Name (given-name), Last Name (family-name), and new-password.

Bookmarklet: Autocomplete Attribute

See source of Autocomplete Attribute bookmarklet

Single Page Application (SPA) Detection

Single Page Applications (SPAs) pose unique accessibility challenges, especially when users navigate between pages. This bookmarklet helps evaluators determine if they are evaluating a multi-page application or a single-page application.

Bookmarklet: SPA Detection

Screen Blank

Toggles a black overlay on top of the current page to assist with screen reader testing.

Bookmarklet: Screen Blank

Character Key Shortcuts (WCAG 2.1 SC 2.1.4)

  1. Open screen reader
  2. Move focus to web page window and press the CTRL key to silence the screen reader
  3. Run the “Remove Page Focus” bookmarklet to ensure that the focus is not on an interactive element
  4. Run the “Trigger Character Key Shortcuts” bookmarklet
  5. Watch the page and listen to the screen reader output to see if any functionality is triggered.
  6. An alert will pop up to notify you when the test is complete
  7. If any functionality is triggered, ensure that there is a mechanism to turn the shortcut off or to remap the shortcut to include one or more non-printable keyboard keys (e.g., Ctrl, Alt). If no mechanism exists, this success criterion fails.

Bookmarklet adapted from 3Needs’ Character key shortcut test page, which was adapted from T-Systems Multimedia Solutions GmbH – Test and Integration Center.

Paul Adam Bookmarklet Collection

Paul Adam maintains an excellent set of accessibility-focused bookmarklets.

Paul Adam Bookmarklets

NVDA Screen Reader

NVDA is the recommended screen reader for evaluating products on Microsoft Windows. It is included in the Software Center in many departments, but if it is not in yours, download it from the NVDA download page.

Colour Contrast Analyser

TPGi’s “Colour Contrast Analyser” software provides one of the easiest ways to test contrast ratio between two colors. Download it from the Colour Contrast Analyser page.

PDF Accessibility Checker (PAC) 2021

PAC 2021 is an automated PDF accessibility checker that checks for conformance with WCAG 2.1. It should be used in tandem with the Adobe Acrobat accessibility checker. Download it from the PDF/UA Foundation PAC 2021 download page.

Photosensitive Epilepsy Analysis Tool (PEAT)

PEAT is used to evaluate web content and software for seizure risk (WCAG 2.1 SC 2.3.1). Download it from the University of Maryland Trace Research & Development Center’s PEAT page