# NDFF invoer vs Observation

The clearest difference is update cadence: Observation at every 2 weeks against NDFF invoer's every 9 months. NDFF invoer's advantage is iOS requirement (10.0 vs 15.1). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

NDFF invoer ships an update every 9 months, Observation every 2 weeks. The most recent releases landed on September 27, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | NDFF invoer | Observation |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 9 months | **Every 2 weeks** |
| Size | 18 MB | 80 MB |
| Requires iOS | **10.0** | 15.1 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [BIJ12](https://appshunter.io/developer/1584095478) | [Stichting Observation International](https://appshunter.io/developer/1464543487) |

## What reviewers say

### NDFF invoer

[App page](https://appshunter.io/ios/app/ndff-invoer/id1068127600)

**Features:** macOS Compatibility

**In-app purchases:** none


### Observation

[App page](https://appshunter.io/ios/app/observation/id6446407612)

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is NDFF invoer free?

NDFF invoer is free to download, with no in-app purchases.

### Is Observation free?

Observation is free to download, with no in-app purchases.

### Do NDFF invoer or Observation have ads?

Neither NDFF invoer nor Observation shows ads.

### Which is updated more often, NDFF invoer or Observation?

NDFF invoer ships an update every 9 months, and Observation every 2 weeks. Most recently, NDFF invoer was updated on September 27, 2026 and Observation on October 10, 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.*