#HTML5 validator.nu vs w3.org/html/check update: recency depends on @hsivonen @sideshowbarker checkins. use both. Update: @jmullan had asked¹ me at my YUIConf HTML5 talk² about whether validator.nu and the W3C's validator were different at all (someone in the audience claimed that W3C's validator just called validator.nu) - the answer is that they both pull from the same source code repository, but not necessarily at the same time, and thus are different enough, often enough, to potentially (and in my experience, sometimes) give different validation results. In addition, w3.org/html/check may also include code from @sideshowbarker's workspace that has not yet been contributed to the repository³. 1^http://twitter.com/jmullan/status/8988393828524032 2^http://ttk.me/b/48t1 3^http://twitter.com/sideshowbarker/status/9049501381693440