# Key4Friends vs BuildSec 4.0

The clearest difference is update cadence: BuildSec 4.0 at every 2 months against Key4Friends's every 9 months. BuildSec 4.0 also leads on iOS requirement (16.4 vs 26.0). 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.

Key4Friends ships an update every 9 months, BuildSec 4.0 every 2 months. The most recent releases landed on November 2, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Key4Friends | BuildSec 4.0 |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 9.1% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 9 months | **Every 2 months** |
| Monetization | Free | — |
| Size | 61 MB | 205 MB |
| Requires iOS | 26.0 | **16.4** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [SimonsVoss Technologies GmbH](https://appshunter.io/developer/1141846652) | [Telenot Electronic GmbH](https://appshunter.io/developer/401623741) |

## What reviewers say

### Key4Friends

[App page](https://appshunter.io/ios/app/key4friends/id1141846653)

Easily and securely share access to doors with friends and family. Receive authorizations from the MobileKey app to open and close designated doors directly from your smartphone. Requires an internet connection for operation.

**Highlights:** Receive digital door keys, Open and close authorized doors, Secure key distribution, Easy friend sharing, Email and SMS verification

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

**In-app purchases:** none


### BuildSec 4.0

[App page](https://appshunter.io/ios/app/buildsec-40/id1472711329)

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

**In-app purchases:** none


## Frequently asked questions

### Is Key4Friends free?

Key4Friends is free to download, with no in-app purchases.

### Is BuildSec 4.0 free?

BuildSec 4.0 is free to download, with no in-app purchases.

### Do Key4Friends or BuildSec 4.0 have ads?

Neither Key4Friends nor BuildSec 4.0 shows ads.

### Which is updated more often, Key4Friends or BuildSec 4.0?

Key4Friends ships an update every 9 months, and BuildSec 4.0 every 2 months. Most recently, Key4Friends was updated on November 2, 2026 and BuildSec 4.0 on November 3, 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.*