Google Chrome offers typing tutorials in the form of extensions, the most recommended being Type Fu and TypingClub. Other online options that are not browser-specific include keybr.com, Typing.com, and RapidTyping.com.
Two other sources of typing tutorials are TypingSoft.com and TypingTutor-online.com. TypingSoft.com advertises itself as listing every online, freeware, and shareware touch typing tutorial in existence. Reviews are provided for some, but not all, of the typing tutorials listed. Every listing includes a link to the tutorial's website.
TypingTutor-online.com is an especially valuable resource because its designers are aware that QWERTY is not the only keyboard layout in use. In addition to offering a choice of keyboards, the site also offers a choice between character, sample text, and user-provided text typing exercises.