Heading Ordering Checker
This heading levels checker linearises each page and checks the order of headings. It will give a warning for each improperly ordered heading. It is advisable to make sure that your page validates before using this utility, as improperly matched headings, or headings within headings could cause problems.
It assumes that a break in the headings numbering (e.g. a <h2> followed by a <h4>) is always wrong, though there are very rare circumstances, where the headings are being used to represent layers of an externally-defined hierarchy, in which this may be reasonable.