Free to use, no sign-up, works on any phone.
It is a 20-lesson touch-typing course, not a timed test. Lesson 1 starts on the home row with F and J, and later lessons move to the top row, bottom row, Shift, the number row and symbols. A lesson ends when you finish its line of text, and the next one loads automatically about two seconds later.
Before every character the key you need lights up on the on-screen keyboard and the matching finger lifts on the hand diagram, with left-hand keys tinted blue and right-hand keys green. When you press a key, that finger and key flash, so you can confirm you used the right finger without looking down at your own keyboard.
The character turns red, an error sound plays, and the cursor stays where it is until you type the correct character, so Backspace cannot undo a mistake and simply counts as another keystroke. Correct keys play a click sound, and since the page has no mute control, mute the browser tab if you want to practise silently.
WPM is the characters you have completed in the current lesson divided by five, divided by the minutes elapsed since your first keypress, so the clock starts when you start typing. Accuracy is correct keystrokes as a share of every keystroke you made. Both figures reset to 0 WPM and 100 percent whenever you switch to another lesson.