Redline: Sprint Timer

The sprint workout, made simple. Free, for iPhone and Apple Watch.

Redline is a free sprint interval timer with nothing in the way. No account, no login, no feed, no subscription, no ads. Pick how many sprints you want, press start, and go run. The countdown, the voice in your ear, the tap on your wrist, the workout in Apple Health: all of it just happens.

WHY SPRINT INTERVALS

Thirty seconds flat out, a real rest, and again. It builds speed, top end fitness and power faster than anything else you can do in running shoes. The hard part was never the sprinting. It was keeping track of it while you are bent over gasping. That is the one job Redline does, and it does it well.

SET IT IN THREE TAPS

One to ten sprints. Fifteen to sixty seconds each. One to ten minutes of rest. Six sprints of thirty seconds with three minutes between them is the classic session and it is the default, so most days you just hit start.

IT TALKS, SO YOU NEVER LOOK DOWN

A ten second lead-in gets you to the line. Then a voice calls every moment that matters. Go. Halfway. Stop. Recover, three minutes. Ten seconds. The cues play right over Spotify, Apple Music or your podcast, with nothing to connect and nothing to set up. Lock the phone, put it in your pocket, and it keeps talking.

MADE FOR APPLE WATCH

Redline runs on Apple Watch as a full workout on its own. Leave the phone in the car, hit start on your wrist, and every transition arrives as a tap, plus the voice cues if you have AirPods in. Your settings stay in sync between the two, and a session finished on either one shows up in the same history.

ON YOUR LOCK SCREEN

A Live Activity keeps the current sprint and the time remaining on your Lock Screen and in the Dynamic Island, so a glance in the middle of a rest tells you exactly what is next.

SAVES TO APPLE HEALTH

Every finished session is saved to Apple Health as a high intensity interval workout, with a segment for every sprint. Run it from the Watch and it records heart rate and energy too. Redline also keeps a simple history and a day streak, stored on your phone and nowhere else.

WHY THERE IS NO SKIP BUTTON

The rest is the training. Thirty seconds is about as long as anyone can hold a true all-out effort, and the last sprint only counts if you are actually recovered when you start it. So Redline makes you wait. You will thank it on sprint six.

ONE HONEST NOTE

Redline is a timer, not medical advice. All-out sprinting is hard on the body. Warm up properly, and check with a doctor first if you have any reason to.

Free. No ads. No subscription. No tracking. Just sprints.