# Key vs Theresa

The clearest difference is update cadence: Theresa at fortnightly against Key's every 4 months. Theresa also leads on iOS requirement (15.0 vs 17.0). 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.

Key ships an update every 4 months, Theresa fortnightly. The most recent releases landed on November 2, 2026 and November 8, 2026 respectively.

## The numbers

| Metric | Key | Theresa |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Fortnightly** |
| Monetization | Free | — |
| Size | 18 MB | 10 MB |
| Requires iOS | 17.0 | **15.0** |
| Devices | iPhone, iPod, Apple Watch | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Interflex Datensysteme GmbH](https://appshunter.io/developer/1150331434) | [QUIS AG](https://appshunter.io/developer/1626966150) |

## What reviewers say

### Key

[App page](https://appshunter.io/ios/app/key/id1150331435)

Transform your iPhone into a mobile ID card for convenient door access. Securely register your credentials and use your phone to open doors, leveraging advanced encrypted transfer technology.

**Highlights:** Smartphone as mobile ID, Convenient door opening, Secure credential transfer, iPhone integration, Requires Interflex software

**In-app purchases:** none


### Theresa

[App page](https://appshunter.io/ios/app/theresa/id6736680819)

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

**In-app purchases:** none


## Frequently asked questions

### Is Key free?

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

### Is Theresa free?

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

### Do Key or Theresa have ads?

Neither Key nor Theresa shows ads.

### Which is updated more often, Key or Theresa?

Key ships an update every 4 months, and Theresa fortnightly. Most recently, Key was updated on November 2, 2026 and Theresa on November 8, 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.*