# Flow21 Systems vs Koala

The clearest difference is in-app purchases: Flow21 Systems at none against Koala's 4. Koala's advantage is update cadence (every 10 days vs every 2 months) and iOS requirement (13.0 vs 16.6). On price, ads and device support there is nothing between them.

Both are free to download. Koala sells 4 in-app purchases, starting at $9.99 per month. Flow21 Systems asks for nothing beyond the download.

Flow21 Systems ships an update every 2 months, Koala every 10 days. The most recent releases landed on October 16, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | Flow21 Systems | Koala |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/koala-appointment-scheduler/id6741917787/reviews)** |
| Number of ratings | — | **1** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 10 days** |
| Monetization | — | Free with in-app purchases |
| Size | 335 MB | 68 MB |
| Requires iOS | 16.6 | **13.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 17+ | 4+ |
| Developer | [Flow21 Systems](https://appshunter.io/developer/1785598054) | [Abhinaba Chatterjee](https://appshunter.io/developer/1796187527) |

## What reviewers say

### Flow21 Systems

[App page](https://appshunter.io/ios/app/flow21-systems/id6739488079)

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

**In-app purchases:** none


### Koala

[App page](https://appshunter.io/ios/app/koala-appointment-scheduler/id6741917787)

Streamline your business operations with an all-in-one appointment management solution. Easily handle bookings, client information, team collaboration, and generate performance reports. Stay organized and grow your service-based business.

**Highlights:** Smart scheduling and reminders, Online booking link, Cloud-based syncing, Service menu management, Client database and history, Quick business reports, Unlimited team members

**Features:** macOS Compatibility

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Silver | $9.99 | per month |
| Gold | $14.99 | per month |
| Platinum | $29.99 | per month |
| Diamond | $49.99 | per month |


## Frequently asked questions

### Is Flow21 Systems free?

Flow21 Systems is free to download, with no in-app purchases.

### Is Koala free?

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

### Do Flow21 Systems or Koala have ads?

Neither Flow21 Systems nor Koala shows ads.

### Which is updated more often, Flow21 Systems or Koala?

Flow21 Systems ships an update every 2 months, and Koala every 10 days. Most recently, Flow21 Systems was updated on October 16, 2026 and Koala on October 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.*