# Halflife vs StackDays

The clearest difference is ads: Halflife at none against StackDays's shown. On price, update cadence, in-app purchases and device support there is nothing between them.

Both are free to download. Halflife sells 3 in-app purchases, starting at $9.99 per 7 days and StackDays sells 3 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.

Halflife ships an update every 6 days, StackDays weekly. The most recent releases landed on November 5, 2026 and November 6, 2026 respectively.

## The numbers

| Metric | Halflife | StackDays |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.9 (72 ratings)](https://appshunter.io/ios/app/halflife-peptide-and-glp-1-log/id6763921857/reviews)** | — |
| Number of ratings | **72** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | **No** | Yes |
| Update frequency | **Every 6 days** | Weekly |
| Monetization | Freemium | — |
| Size | 59 MB | 97 MB |
| Requires iOS | **15.1** | 15.3 |
| Devices | iPhone, iPod | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Ziad Soliman](https://appshunter.io/developer/1892230531) | [RHH LLC](https://appshunter.io/developer/1881934615) |

## What reviewers say

### Halflife

[App page](https://appshunter.io/ios/app/halflife-peptide-and-glp-1-log/id6763921857)

Manage complex health protocols involving peptides, TRT, and longevity compounds. Track dosing, inventory, and biological effects with detailed pharmacokinetic modeling. Integrates with Apple Health for comprehensive wellness insights.

**Highlights:** Multi-compound protocol tracking, Pharmacokinetic concentration curves, Dose scheduling and adherence, Vial inventory management, Syringe calculator, Apple Health integration, Compound database

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Halflife Premium | $9.99 | per 7 days |
| Halflife Pro Annual | $34.99 | per year |
| Halflife Pro Annual | $44.99 | per year |


### StackDays

[App page](https://appshunter.io/ios/app/stackdays-habit-tracker/id6796375407)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Pro | $2.99 | per month |
| Annual Pro | $24.99 | per year |
| Lifetime Pro | $59.99 | one-time |


## Frequently asked questions

### Is Halflife free?

Halflife is free to download, with in-app purchases available.

### Is StackDays free?

StackDays is free to download, with in-app purchases available.

### Do Halflife or StackDays have ads?

StackDays shows ads; Halflife does not.

### Which is updated more often, Halflife or StackDays?

Halflife ships an update every 6 days, and StackDays weekly. Most recently, Halflife was updated on November 5, 2026 and StackDays on November 6, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*