HTML Tidy is a program, which helps to find errors in HTML documents and to perform some actions on HTML pages, such as "convert tags to lowercase", "convert document to XHTML form", "reformat for better readability" etc.
It is available as plugin (install it via "Addons Manager").
Plugin commands are:
- "Menu": allows to call Tidy action. Actions are configurable in text files.
- "Validate document": the Validation tab of Output panel will show you the list with
errors and warnings in HTML code. You can double-click lines in this list to go to the source code.
- "Browse configs": shows list of text files, one file per Tidy action, you can edit them or add new files.