Comparison

STRENGTH LAB vs Castra App

Price, ratings, monetisation and update history for both apps, side by side โ€” with what reviewers say about each.

Head to head
About

STRENGTH LAB

Features
Read full description

Strong Women | Strong World Transform your body and your life with Coach Julia's private coaching app, Strength Lab. Focused on science based strength training and sustainable nutrition to help women achieve lasting results. Our app offers personalized exercise plans that are tailored to your unique fitness goals, with seamless workout tracking and progress updates sent directly to your Coach. Strength Lab also provides custom nutrition plans, complete with a food database and macro tracking, as well as supplement plans and tracking. Our video exercise library provides expert demonstrations, and our in-app weekly check-in form connects directly to your coach which keeps you accountable and motivated. Plus, you'll have direct access to your coach through our in-app messaging feature. And that's not all - COMING SOON - We will offer integration with wearable fitness devices to make tracking your progress even easier! Join us at Strength Lab and let's build a better world, one strong woman at a time. * App access requires paid coaching plan Terms of use: https://kahunas.io/terms-conditions Privacy policy: https://kahunas.io/privacy

About

Castra App

Features
Read full description

The platform where fitness coaches seamlessly manage clients and everyone can discover motivation for free FEATURES: - Log your workout with a simple and easy to use interface - Ready to use workouts to get you started, or get a personalized AI-generated plan the moment you sign up - Hundreds of exercises in our library or create your own - Create your own custom exercises for your workouts - Follow and copy your friends workout - Analyze your workout in details with charts and graphs - Analyze your body measure progress - Lead or join your dream team of athletes, or discover and join public communities and challenges - Manage your clients workouts and track their performance - Send and track check-ins and custom forms with your clients - Find your coach that will help you achieve your dream body, and book their sessions and services directly - Share your workouts and achievements as branded images to Instagram, Facebook and beyond - Chat with your coach or clients in real time ATHLETE: - Unlimited workouts per day - Unlimited custom exercises - Unlimited Graph History - Instantly connect with coaches - Book coaching sessions and services - Join challenges and earn rewards - Support our small team COACH: - Lead your own team of athletes - Manage and organize your clients workouts - Assign and review check-ins and custom forms - Publish bookable services and manage your schedule - Chat with your clients in real time - Support our small team Th Athlete and Coach subscriptions automatically renews if you do not cancel it at least 24 hours before the end of the current subscription period. Your account will be charged for the next subscription period up to 24 hours prior to the current subscription's expiration. You can manage your subscription and disable automatic renewal at any time by adjusting your Apple account settings. You have the right to withdraw from your initial subscription within 14 days of starting it. By purchasing, you accept our Tems & Conditions and Privacy Policy. Terms & Conditions https://castra.app/terms-and-conditions/ Privacy Policy https://castra.app/privacy-policy/ Own your journey!

Screenshots

STRENGTH LAB3 screens
Castra App4 screens

Verdict

The call

The clearest difference is update cadence: Castra App at weekly against STRENGTH LAB's every 6 weeks. On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. STRENGTH LAB sells 1 in-app purchase, starting at $250.00 per month and Castra App sells 4 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

STRENGTH LAB ships an update every 6 weeks, Castra App weekly. The most recent releases landed on October 19, 2026 and October 22, 2026 respectively.

Scorecard1 real difference ยท 5 level
STRENGTH LAB versus Castra App: the parameters behind the verdict, then further details
ParameterSTRENGTH LABCastra App
PriceFreeFree
Update frequencyEvery 6 weeksWeekly โ€” better
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, iPod โ€” betteriPhone, Apple Watch
Requires iOS15.0 โ€” better16.6
Further details โ€” not scored
Size52 MB66 MB
Age rating17+17+
DeveloperJJB Enterprises, Inc.CASTRA APP OOD

In-app purchases

1 purchases

STRENGTH LAB

Subscriptions1
  • Monthly Coaching$250.001 Month
4 purchases

Castra App

Subscriptions4
  • Athlete Subscription14 Days trial$4.991 Month
  • Coach Monthly Subscription14 Days trial$29.991 Month
  • Athlete Annual Subscription14 Days trial$49.991 Year
Show 1 more
  • Coach Yearly Subscription14 Days trial$269.991 Year

Questions

Is STRENGTH LAB free?
STRENGTH LAB is free to download, with in-app purchases available.
Is Castra App free?
Castra App is free to download, with in-app purchases available.
Do STRENGTH LAB or Castra App have ads?
Neither STRENGTH LAB nor Castra App shows ads.
Which is updated more often, STRENGTH LAB or Castra App?
STRENGTH LAB ships an update every 6 weeks, and Castra App weekly. Most recently, STRENGTH LAB was updated on October 19, 2026 and Castra App on October 22, 2026.

Other comparisons