It's easy to have mistakes creep into your HTML documents, and one of the best free, automated ways to target mistakes and fix them is HTML Tidy. A group of open-source volunteers keeps this program fresh. The program can automatically clean up most types of HTML mistakes you make, but it also alerts you when it has no fix and points to what you need to fix yourself. If you're into maximum control, you can tell HTML tidy to do nothing but point to errors so that you can fix them. You can see examples of how the program works online.
Especially if you use and reuse the same HTML templates a lot, you can end up with a lot of advertisement-related baggage, unwanted frames, and scripts that you don't need and more. To clean these kinds of unwanted items out of an HTML file automatically, try HTML Stripper. It's a free application, and is especially good at weeding out frames and scripts that have become extraneous in a document.
For HTML documents containing many URLs, utilities that can check a large group of them and identify any broken links can be very helpful. I like Link Sleuth for this application. It can produce reports that summarize broken links, identify redirected links, and more.
Do you know of any good, free HTML utilities?
Shailesh Patel uses OStatic to support Open Source, ask and answer questions and stay informed. What about you?