Build muscle & lose weight fast.

Download for FreeAvailable on iPhone + Apple Watch
Flex AI app
Loose weight with Flex AI
Gain weight with Flex AI
Flex AI fitness
Cardio with Flex AI
Flexibility with Flex AI
Increase strength with Flex AI

Free. Fun. Effective.

The fastest way to build muscle or lose weight, for free! We make it easy to form a workout habit with game-like features and automatic progression of your exercises.
Turn the gym into a game.

Turn the gym into a game.

Hit personal records, compete with friends on leaderboards and see how you rank among others similar to you. Whatever you do, don't lose your workout streak!
Connect with others.

Connect with others.

Join the community and show off your progress pictures! Get motivated and participate in discussions around improving your fitness.
Simple tracking & sharing.

Simple tracking & sharing.

Find, build, share your own exercises and workouts with full customizability. Plan your workouts into a routine and then share them with friends!

More to love

Easy to use

Automatic progression

Body weight tracker

Plate calculator

Music control

Get fit with Flex

Download for FreeAvailable on iPhone + Apple Watch
4.7
On the App Store
Let me start by saying this is the best free app period. There is no free app that can beat this. I've tried every other one I could find and this is by far the best.
SteveW123456789
Has everything needed; it's clear, organized, detailed and well rounded. It's obvious the developers are actually into fitness and know what they're doing. Definitely recommend this app!
milad23
I continue to be super impressed with this app. The free version lets you build out your own workouts and the timer helps me get 2x done in the gym than what I would before this app.
D_R_Farrell