Flux vs Ester
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Flux
This app helps you train smarter by generating personalized workouts based on your goals, available equipment, and time. It uniquely adapts to your progress over time, keeping all your data on your device for privacy. Track every set, rep, and weight with ease, and benefit from advanced features like progressive overload and fatigue-aware training.
- Personalized workout generation
- Customizable routines and exercises
- Real-time adaptive changes
- Progressive overload and periodisation
- Fatigue-aware training support
- Apple Health integration
- Data export
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Walk into the gym with a plan. Leave knowing what to aim for next. Flux creates personalized gym routines around your goals, experience, schedule, session length and available equipment. See your whole workout in one scrolling view, log sets with less screen switching and keep past performance close when choosing your next targets. TRY EVERY FEATURE FREE Download Flux free and use every feature for 14 days. No payment is required, the trial does not start a subscription and there is no automatic charge. UNLOCK FOREVER After the trial, training features require a one-time Lifetime Unlock. There is no free training tier after the trial and no recurring charge. Apple shows the price for your storefront before you confirm. Eligible existing paid owners keep permanent Full Access. PLAN AROUND YOUR LIFE - Generate Push/Pull/Legs, Upper/Lower, Full Body and other routines - Match training to your equipment, schedule and available weight increments - Choose a session length from 30 to 90 minutes when generating a routine - Build your own routines and custom exercises - Browse prebuilt programs with Overview, Guide and Settings before choosing - Follow Flux Hybrid for strength and timed cardio - Swap exercises for a workout or across the remaining program where supported CHOOSE YOUR STRENGTH PERIODIZATION - Adaptive Block: goal-appropriate phases with completion and recovery checks - Daily Undulating: different strength-day emphases across your routine - Linear: a six-week progression of training emphasis - Weekly Undulating: routine-wide emphasis that changes by model week - Manual: choose an eligible phase, with safety recovery when needed Choose a model when generating a strength routine. To change models, generate a new routine. Prebuilt programs keep their authored progression; HIIT keeps its timed prescription. Personalized features need calibration and sufficient training history. FOLLOW YOUR WORKOUT IN ONE PLACE - Log sets with less screen switching and see what is done and what comes next - Keep warm-ups and working sets together, with rest timers and set targets - Move on easily: the next unfinished exercise comes into view automatically - Use individual set targets, supersets, drop sets, myo-reps and giant sets - Add sets and notes, or open Edit, Swap and Remove from your workout - Review achieved sets, missed targets, next-session guidance and trained muscles in Workout Complete EDIT SETS AND CHECK PROGRESS IN ONE PLACE Choose your next targets with past performance close by. Edit sets in Settings, then switch to Stats in the same exercise details screen for performance charts, volume trends and previous workouts. Pick a date range to see recent sessions or the longer trend. Available from your workout, Next Up or saved routine, with history across routines. Future prebuilt target restrictions still apply. UNDERSTAND YOUR TRAINING - Review Strength, Health, Consistency and Targets hit in Insights - Follow your current routine from the day you started it - Revisit findings saved with your Check-in reports - See your training phase and position in Routine Overview - Use optional Apple Health sleep, HRV and heart-rate context - Export training data and use optional signed-in cloud backup MAKE FLUX YOURS Choose System, Light or Dark in Profile > Theme. Signed-in choices sync; System follows each device. Home widgets and Live Activities follow where iOS permits. Log offline with valid access. An already-open workout can be finished after trial expiry; returning after expiry shows the paywall. Restore Purchases and Account & Data remain available. Cloud backup syncs separately when online. Apple Health is optional. Learn more: https://fluxworkouts.com Support: https://fluxworkouts.com/support Terms: https://fluxworkouts.com/terms Privacy: https://fluxworkouts.com/privacy
Ester
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Ester is a private tracker for physician-prescribed hormone and peptide therapy - TRT, GLP-1 medications, and other injectable or oral treatments. Log doses in two taps, see estimated medication levels, keep your lab work in context, and watch your real progress. START WITH 7 DAYS FREE Every feature is included with an Ester Pro subscription, and new subscribers get a 7-day free trial. EVERYTHING STAYS ON YOUR DEVICE No account. No server. No analytics. Your data never leaves your phone - we could not hand it over if we wanted to. Lock the app with Face ID and choose a discreet home-screen icon. LOG IN TWO TAPS A daily checklist with reminders, streaks, and injection-site rotation history. Vial inventory tracks what you have on hand, how much is left, and when you'll run out. ESTIMATED LEVELS A levels chart estimates active medication from the doses you log, using published half-life values. Solid past, projected future, a steady-state badge - and a washout view when a treatment period ends. LABS IN CONTEXT Record blood panels with editable reference ranges. Trends show every marker against your treatment timeline, and values outside your reference range are flagged. RECEIPTS FOR YOUR PROTOCOL Report cards summarize each treatment period: weight, body composition, strength, lab changes, and adherence. Compare periods side by side and share progress cards with medication names hidden by default. ESTER NEVER GIVES ADVICE Ester tracks and visualizes data you enter. It does not recommend medications, doses, or schedules, and it is not a substitute for medical care. Always consult your physician. Ester requires an auto-renewing Ester Pro subscription ($4.99/month or $29.99/year). New subscribers get a 7-day free trial. Subscriptions renew unless cancelled in your App Store settings. Your data stays on your device even if your subscription ends. Terms: https://castanedanetworks.com/ester/terms Privacy: https://castanedanetworks.com/ester/privacy
Screenshots
Verdict
The clearest difference is iOS requirement: Ester at 18.0 against Flux's 26.2. On price, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Flux sells 4 in-app purchases, starting at $2.99 per month and Ester sells 2 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.
| Parameter | Flux | Ester |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 1 — better | — |
| Update frequency | Weekly | — |
| Ads | No | No |
| In-app purchases | Yes | Yes |
| Monetization | Freemium | — |
| Devices | iPhone | iPhone |
| Requires iOS | 26.2 | 18.0 — better |
| Further details — not scored | ||
| Size | 47 MB | 3 MB |
| Age rating | 4+ | 12+ |
| Developer | Digital Flux Ltd | Castaneda Networks LLC |
In-app purchases
Flux
- Flux Pro : 1 Month$2.991 Month
- Flux Pro : 12 Month$19.991 Year
- Flux Pro : Lifetime Pass - Founder$49.99
- Flux Pro : Lifetime Pass$59.99
Ester
- Ester Pro7 Days trial$4.991 Month
- Ester Pro7 Days trial$29.991 Year









