Stackd vs Halvo
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Stackd
This app allows you to import AI-generated workout and meal plans directly into a tracking interface. Log your sessions, monitor progress with strength charts, and track nutrition macros all in one place without manual template entry.
- Import AI workouts via JSON
- Log sets, reps, and weight
- Automatic weight recommendations
- Estimated 1-rep max charts
- Full session history
- Nutrition and macro tracking
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Training phases change. Work gets busy. Goals shift. Most fitness apps lock you into their programs. Stackd works with whatever plan you built this week — because your AI agent writes it, and Stackd just keeps score. IMPORT AI WORKOUTS IN SECONDS Design your program in any AI agent. Copy the JSON. Paste it into Stackd. Your full workout plan appears instantly — exercises, sets, rep targets, everything. No manual entry. No templates. No friction. TRACK EVERY SESSION Log sets, reps, and weight as you train. Stackd auto-fills your last session's weight so you always have a starting point. Hit your rep targets and the weight recommendation updates automatically — progressive overload built in. SEE YOUR STRENGTH GROW Estimated 1-rep max charts for every exercise. Watch your squat, bench, and deadlift climb week over week. Full session history so you never lose a workout. NUTRITION TRACKING INCLUDED Log meals and hit your macro targets without switching apps. Build daily meal plans, track protein, carbs, and fat. Everything in one place. BUILT FOR LIFTERS WHO PLAN WITH AI Most fitness apps want to sell you their programs. Stackd assumes you already know how to use AI Agents to build a better one. We just give those programs a home. No ads. No upsells inside the app. Cancel anytime.
Halvo
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Your last coffee decides your night. Halvo shows you how much caffeine is actually working in you right now — and tells you the point after which the next cup starts costing you sleep. Your personal cut-off. Most caffeine apps count milligrams. Halvo works with the caffeine that actually reaches your system: it rises, peaks and fades. Halvo predicts how much of it is still there when you go to bed. YOUR PERSONAL CUT-OFF Everyone clears caffeine at a different speed. Halvo shows you the latest you can have a cup without too much of it still active when you fall asleep. LOG IN SECONDS Add coffee, espresso, tea, energy drinks, soda, mate or your own pre-workout in a few taps. Halvo sums it up automatically and shows how much is still working. ON YOUR HOME SCREEN AND ON YOUR WRIST The widget shows your level and your cut-off without opening the app — one tap logs your favourite drink. In the evening it switches to "lights out" on its own. Plus Apple Watch with a complication for a glance-and-go check. SEE YOUR CURVE Watch caffeine rise, peak and fade on a real concentration curve — and see exactly where you'll land when your head hits the pillow. A MODEL THAT LEARNS YOU — HONESTLY (PRO) With your permission, Halvo reads your sleep, heart rate and HRV from Apple Health and learns your personal caffeine half-life over time. Here's what makes it different: when the signal in your data is too weak to be sure, Halvo says so and keeps using the population value — instead of faking precision it doesn't have. WORKS WITH YOUR WEARABLES (PRO) Apple Watch, Oura, Whoop, Garmin — anything that syncs sleep and heart data to Apple Health. Halvo never connects to those services directly; it only reads what's already in Apple Health. PRIVATE BY DESIGN Your intake and health data are processed on your device. Halvo doesn't sell your data. FREE & PRO Logging caffeine, seeing your curve, using the widget and finding your cut-off are free. Halvo Pro adds the personal learning model and the nightly sleep analysis. Halvo Pro: • Monthly – $3.99 • Yearly – $24.99 (with 1 month free) • Lifetime – $44.99 one-time (no subscription) Payment is charged to your Apple Account. Subscriptions renew automatically unless canceled at least 24 hours before the end of the current period. Manage or cancel anytime in your Apple Account settings. Lifetime is a one-time purchase. Prices may vary by region. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://halvo.jnmcloud.de/privacy.html Halvo is not a medical device and does not diagnose, treat or prevent any condition. It helps you make more informed choices about caffeine.
Screenshots
Verdict
The clearest difference is in-app purchases: Stackd at none against Halvo's 2. Stackd also leads on update cadence (daily vs monthly). Halvo's advantage is iOS requirement (17.0 vs 26.2). On price, ads 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. Halvo sells 2 in-app purchases, starting at $3.99 per month. Stackd asks for nothing beyond the download.
Stackd ships an update daily, Halvo monthly. The most recent releases landed on October 3, 2026 and October 10, 2026 respectively.
| Parameter | Stackd | Halvo |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (2 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 2 — better | — |
| Update frequency | Daily — better | Monthly |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone | iPhone, Apple Watch — better |
| Requires iOS | 26.2 | 17.0 — better |
| Further details — not scored | ||
| Size | 9 MB | 8 MB |
| Age rating | 17+ | 4+ |
| Developer | Jovan Petrovic | Jan Niklas Molleken |
In-app purchases
Stackd
No in-app purchases
Halvo
- Halvo Pro – Monthly$3.991 Month
- Halvo Pro Lifetime$29.99









