# Fastyn vs NPD对抗21天

The clearest difference is update cadence: Fastyn at every 3 months against NPD对抗21天's every 10 months. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Fastyn sells 3 in-app purchases, starting at $1.99 per 7 days and NPD对抗21天 sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Fastyn ships an update every 3 months, NPD对抗21天 every 10 months. The most recent releases landed on October 28, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Fastyn | NPD对抗21天 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 3 months** | Every 10 months |
| Size | 35 MB | 5 MB |
| Requires iOS | 17.6 | 17.6 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 17+ | 4+ |
| Developer | [MANUEL MATAS GALEOTE](https://appshunter.io/developer/1794633190) | [阳 孙](https://appshunter.io/developer/1518808403) |

## What reviewers say

### Fastyn

[App page](https://appshunter.io/ios/app/fastyn-intermittent-fasting/id6744653719)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Fastyn Plus Weekly | $1.99 | per 7 days |
| Fastyn Plus Monthly | $3.99 | per month |
| Fastyn Plus Annual | $17.99 | per year |


### NPD对抗21天

[App page](https://appshunter.io/ios/app/npd21/id6757114144)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| NPD对抗21天 Pro | $0.99 | one-time |


## Frequently asked questions

### Is Fastyn free?

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

### Is NPD对抗21天 free?

NPD对抗21天 is free to download, with in-app purchases available.

### Do Fastyn or NPD对抗21天 have ads?

Neither Fastyn nor NPD对抗21天 shows ads.

### Which is updated more often, Fastyn or NPD对抗21天?

Fastyn ships an update every 3 months, and NPD对抗21天 every 10 months. Most recently, Fastyn was updated on October 28, 2026 and NPD对抗21天 on October 30, 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.*