Peak Interval vs GymNext Flex Timer: The App, the Hardware, and What You Pay For

If you have trained in a CrossFit box, you have probably seen a GymNext Flex Timer: the big LED clock on the wall, started from a coach's phone. The GymNext app is how that clock gets programmed, and it also runs as a standalone timer on your own phone, which is how a lot of people who never owned the hardware ended up using it for years.

That history explains both what GymNext does very well and why some long-time users have soured on it. One user of eight years on r/crossfit described opening the app to an intro video and a sign-in prompt where there used to be none, and finding that switching the video off led to a subscription screen. So the real question is not which timer has more modes. It is whether you want a timer app or the remote control for a wall unit.

What GymNext is built around

GymNext's centre of gravity is the hardware. The app pairs with the Flex LED display, which runs roughly $150 to $300 depending on the edition, and the app's modes — count up and down, rounds, Tabata, EMOM, mixed intervals, sets with rest — map onto what the wall clock can show. It can also play cues through a Bluetooth speaker so the whole room hears the buzzer.

The app is free to download, with a Pro tier at $8.99 a month or $79.99 a year on the US App Store at the time of writing. Recent versions added AI timer building from text, voice or a photo, custom voice prompts, workout QR sharing and an Apple Watch app. An account is used to sync favourites and plans between devices.

If you coach a class or train in a box that already has a Flex on the wall, that combination is hard to beat. Thirty people can read the same four-inch digits, and the coach starts everything from one phone. No phone-first app replaces that.

What Peak Interval is built around

Peak Interval has no hardware to sell, so the whole product is the workout on your phone and wrist. You build a session from phases — prep, work, rest, cooldown, repeated sets nested inside blocks — save it, and run it from the iPhone or the Apple Watch with the phone left in your bag.

The design bet is that, for one person training alone, the cues matter more than the digits. Each phase gets its own audio and haptic cue, so you hear and feel the change from work to rest without looking up. That covers the same problem the wall clock solves, from a device you already own, and it comes with you to the hotel gym or the track.

Pricing is the other difference. Peak Interval is free to download and offers both a monthly subscription with a free trial and a one-time purchase, so if you would rather not pay every month for a timer, you do not have to.

Where each one wins

Pick GymNext if you own or plan to buy a Flex display, you run classes or partner workouts where several people need to see one clock, or you train in a box that already uses it. The app is at its best as the brain of that clock, and the hardware is a genuine advantage there.

Pick Peak Interval if you train alone, have no wall clock, and mostly want a structured session on your wrist with cues you can hear. That is also the right pick if what pushed you away from GymNext was the account prompt or the subscription: you get saved multi-phase workouts and a Watch flow without paying for features built around hardware you will never mount.

Running both is fine. Plenty of people use the box's Flex timer in class and their own app for the solo sessions at home. The two are not competing for the same moment.

The short version

GymNext is a hardware company with a very capable app, and it is the obvious choice if there is a Flex on your wall. If there is not, you are using the remote without the device. Peak Interval is built for exactly that solo case: a saved workout, cues for every phase, and a one-time purchase if you want one.