W3C Markup Validation Service

Need to feel validated? Well, how about your Website? Chances are, using something like this markup validator might just save you a lot of wasted time and headaches down the road.

What is the Markup Validator and what does it do?

The Markup Validator is a free tool and service that checks the syntax of (X)HTML documents.

The Validator is sort of like lint for C. It compares your HTML document to the defined syntax of HTML and reports any discrepancies.

Learn more about the Markup Validator.
Why should I validate my HTML pages?

One of the important maxims of computer programming is: Be conservative in what you produce; be liberal in what you accept.

Browsers follow the second half of this maxim by accepting Web pages and trying to display them even if they’re not legal HTML. Usually this means that the browser will try to make educated guesses about what you probably meant. The problem is that different browsers (or even different versions of the same browser) will make different guesses about the same illegal construct; worse, if your HTML is really pathological, the browser could get hopelessly confused and produce a mangled mess, or even crash.

That’s why you want to follow the first half of the maxim by making sure your pages are legal HTML. The best way to do that is by running your documents through one or more HTML validators. [Check it out for yourself]