Flex - Fitness Training 4+

Lose Weight, Build Muscle

Flex Artificial Intelligence Inc.

    • 4.7 • 351 Ratings
    • Free
    • Offers In-App Purchases


A free trainer in your pocket. Lose weight or build muscle.

Personalized workout plans
Or build your own
Achieve any fitness goal
Top workout routines & plans built by personal trainers
For any difficulty level

Our goal is to create a healthier world.
Follow us on instagram @flex.ai to join the community!

• Basic workout programs
• Build or customize your own program and freestyle workouts
• Workout guide to log and improve upon your performance each session
• Share your plans and workouts to other people
• View your progress and stay consistent: workout calendar, exercise stats, streak, bodyweight tracker, calories tracker, steps tracker, workout notifications
• Auto Progression: Flex automatically increases or decreases the difficulty of your exercises in your program based on past performance

Flex Premium:
• Logging on the Apple Watch app
• Unlock Premium programs
• Unlock Premium freestyle workouts
• Premium workout experience: music integration, plate calculator, etc.
• Advanced editing/building tools

Flex is the free, simple, and engaging app that does the planning and tracking so that you can just focus on your workouts and achieve your goals. Flex can automatically increase or decrease the difficulty of your exercises in your program based on past performance.

Hundreds of workouts and programs for you. Find and use the most effective workouts and programs designed by personal trainers, tailored to your goal and whether you workout at the gym or at home.

Forget about researching exercises, programs and keeping track of all your progress. Flex handles that and makes working out more engaging with features like streaks and progress charts.

Freestyle workouts:
Whatever your time commitment, physical goals, experience, or access to equipment, Flex has the right workouts for you. Choose any combination of equipment, goals, muscles worked or quick freestyle workouts.

Already have a fitness program you use or want to customize your own?
Edit one of our programs or build your own into Flex with the custom plan builder.

Real-Time Workout Guide:
Flex’s workout guide will lead you through your workout step by step, telling you which exercises to do, how to do them, how long to rest for optimal results and notifying you when you need to start your next set. You also have the spreadsheet view where you can fully modify your workout on the fly. Move around exercises, change exercises, add/remove sets. Control your music without leaving the app thanks to native Spotify and Apple Music integrations.

You can't improve what you don't measure. With Flex, you can track:

How consistently you’re exercising with the calendar feature
Your total calories burned daily, calculated from workouts/steps/BMR
Your bodyweight over time
Your steps with a 10k daily goal via the Apple Health integration
Your exercise progress with the exercise stats
Your workout history

An even easier way to workout with Flex Apple Watch:
Use the Flex apple watch app to log sets and complete workouts without needing to constantly check your phone. Sync your data and close your activity rings.

What’s New

Version 1.14.2

Bug flattening

Ratings and Reviews

4.7 out of 5
351 Ratings

351 Ratings


This is an amazing program

Thank you so much
for helping us to achieve the right work out with out hassle so quick and affordable , it is very simple and helpful for everybody .
Well done

Developer Response ,


Micar ,

Simple And Easy

Full disclosure, I was lucky enough to be part of the beta testing. The app was great through the testing and was nearly flawless and rock solid.
It is easy to set-up, use and track progress. I tried a few others before but found them awkward. I like the ability to link in Apple and Spotify music as well to keep me motivated through my workouts.

Developer Response ,

Thanks for your awesome review 🙏☺️

BigBang13131 ,

Great workout/fitness app!

Was part of the testing. It has come a long way. There are a lot of good programs for everything and anything you want to work on. From overall fitness, fat burning, muscle building and strength.
Workouts and demos are pretty straight forward.
Tracking is good too. No longer need to keep a conventional notebook and pen with you. Just use the app and log your workouts. See your progress.

Keep up the great work!

Developer Response ,

Thank you! We appreciate your review 🙏

App Privacy

The developer, Flex Artificial Intelligence Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer's privacy policy.

Data Linked to You

The following data may be collected and linked to your identity:

  • Health & Fitness
  • Contact Info
  • Identifiers
  • Usage Data
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Some in‑app purchases, including subscriptions, may be shareable with your family group when Family Sharing is enabled.

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