I couldn't find an online timer that I could use for Crossfit and tabata style workouts that looked good on iPad/iPhone, so I made one. Great for home gym enthusiasts.
http://markdaws.net/sports-timer/app
By default when you hit the start button, the timer has a 5 second countdown then starts counting up indefinitely. You can go to the settings page and instead of counting up, set the count down time. When you next start the timer it will instead count down from the specified time to zero.
On a regular timer, if you press the left gray circle you can save a lap time, clicking on the small circle that appears will show you the lap time, clicking again will show the current time.
A popular format for Crossfit workouts is tabata, with 20 seconds of work, 10 seconds of rest, for 8 intervals. You can set your work time, rest time and number of intervals on the settings page.
By default the app is muted, you can press the unmute button at the bottom and then when the timer is counting down it will beep every second from 3, 2, 1 down to 0.
NOTE: If you are playing audio in the background e.g. using Spotify, the beeps do cause the background music app to stop playing which is really annoying, so by default this feature is muted.
NOTE: If you have the app pinned to your home page, the beeps will not play, but they do play if you launch the page in iOS Safari.
The app is a webpage but I would suggest adding it to your home screen as an app. You will then get the timer in full-screen mode each time it launches.
NOTE: On iOS, each time you change between the pinned webpage and another app then back, the webpage will be completely reloaded. This is a limitation of iOS, so if you want to swap between the timer and other apps like your music app during a workout, you probably just want to launch the timer in a regular browser instead of as a pinned app.
http://www.howtogeek.com/196087/how-to-add-websites-to-the-home-screen-on-any-smartphone-or-tablet/
If you are not seeing the correct font when the page loads, or icons are missing, make sure you disable your ad blocker for the app URL.
This app has only been tested on an iPhone, iPad and on Chrome/Mac.
The digital font is freeware and available from the following site: http://www.styleseven.com/