Bobby
A free online accessibility service designed to help expose and repair barriers to accessibility and encourage compliance with existing accessibility guidelines. Submit your web page address and Bobby will analyze it. A comprehensive report will indicate any errors and warnings.

WAVE
A free online accessibility service provided by Temple University. Submit your web page address and WAVE will analyze it. The subsequent report will indicate missing Alt image attributes and point out warnings and errors for other page elements.

A-Prompt Web Accessibility Verifier
A-Prompt (Accessibility Prompt) is a software tool designed to improve usability by evaluating web pages for accessibility barriers and then providing hints to make the necessary repairs. Available for free download (Windows 95, 98, NT, 2000).

HTML Validator
This program runs on Windows-based systems and enables web developers to validate their code locally without the need to submit a web address to a web-based validation service. The program also alerts web developers to some potential accessibility problems. Available as both a fee-based professional version or a free HTML Validator Lite version.

Web Backward Compatibility Viewer
View your Web pages as they appear in a variety of Web browsers.