The program scans every new dump for over 30 languages and creates a list of articles with errors.
For a few Wikipedias, the program scans newly revised articles daily, to create a new list for users, omitting already-corrected articles.
A specific interface – here for the English project – facilitates correcting problems detected by the program in the following three levels of ranking priorities errors. It helps keep the error lists updated in near real time by providing some statistics on corrections made recently.
You can download the Checkwiki programs at GitHub. The programs are licensed under GPLv3.
Interested users might also like to review the regularly-updated lists of wiki syntax issues at Special:LintErrors.
An analysis is also performed by WikiCleanerBot twice a month on the dumps for some of the errors, including some additional errors compared to the project interface.
Bots fix some of the errors here automatically. Any error tagged with "BOT" is usually fixed by bot at some point, so manually fixing them is unnecessary.
Wikipedia:HTML 5 – information page on technical details of updating WP code to HTML 5 + CSS3, including how to replace deprecated HTML 4.01 markup; includes automated searches for obsolete markup
Wikipedia:Linter – MediaWiki extension to identify broken and problematic markup which cannot be fixed automatically by the server