One of the most important parts of online accessibility is making sure that your code is designed to make your website or tool accessible. While there are many basic principles that will help you to design accessible code, an important part of the process is validating your finished code to make sure that the final product is accessible. There are a number of free tools that help with this process. The tools below offer some options for validation.
The Web Accessibility Evaluation Tool (WAVE) by WebAIM offers several different ways to evaluate the accessibility of a website. You can enter the URL for a public site into the form on the website, as seen to the left, but you can also install a browser extension in Chrome or Firefox to test other sites from within your browser window.
Color Oracle is a tool for Windows, Mac OS, and Linux computers that simulates the experience of colorblind users. It is a helpful way to make sure that the colors on your web content will be accessible to the widest possible range of viewers and a great way to understand how individuals who are colorblind experience the web.
The WCAG Compliance Auditor tests code for compliance with various standards and generates charts and reports as an output. This is a great way to create a record of the process of creating and validating your code.
AChecker, also known as Accessibility Checker, is an open source tool for checking the accessibility of websites and code files. The tool is free and very easy to use. It is available in English, German and Italian.
The Color Contrast Checker from WebAIM allows users to check various combinations of hexadecimal values to determine which will be accessible to users with visual impairments. It allows you to evaluate both normal and large text. At the bottom of the page, it also offers links to other recommended tools.