# Danify, Danish Exam Prep vs Big O Notation

The clearest difference is in-app purchases: Big O Notation at none against Danify, Danish Exam Prep's 10. On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. Danify, Danish Exam Prep sells 10 in-app purchases, starting at $9.99 per month. Big O Notation asks for nothing beyond the download.

## The numbers

| Metric | Danify, Danish Exam Prep | Big O Notation |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 months | — |
| Size | 97 MB | 38 MB |
| Requires iOS | 15.1 | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Alejandro Villanueva](https://appshunter.io/developer/1851064447) | [AFTW LLC](https://appshunter.io/developer/1886356149) |

## What reviewers say

### Danify, Danish Exam Prep

[App page](https://appshunter.io/ios/app/danify-danish-exam-prep/id6754946068)

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

**In-app purchases (10)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Danish Citizenship Subscription | $9.99 | per month |
| Active Citizen Subscription | $9.99 | per month |
| Active Citizen Subscription wT | $9.99 | per month |
| Danish Citizenship Subscription wT | $9.99 | per month |
| Token Pack 50 | $5.99 | one-time |
| Danish Citizenship Current Session | $9.99 | one-time |
| Active Citizen Exam Current Session | $9.99 | one-time |
| Token Pack 200 Description | $19.99 | one-time |
| Danish Citizenship 26 Winter | $39.99 | one-time |
| Active Citizen Exam - Winter 2026 | $39.99 | one-time |


### Big O Notation

[App page](https://appshunter.io/ios/app/big-o-notation/id6771656290)

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

**In-app purchases:** none


## Frequently asked questions

### Is Danify, Danish Exam Prep free?

Danify, Danish Exam Prep is free to download, with in-app purchases available.

### Is Big O Notation free?

Big O Notation is free to download, with no in-app purchases.

### Do Danify, Danish Exam Prep or Big O Notation have ads?

Neither Danify, Danish Exam Prep nor Big O Notation shows ads.

---

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