# E4 Flex vs RubberSource

The clearest difference is update cadence: RubberSource at every 3 weeks against E4 Flex's every 21 months. 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.

E4 Flex ships an update every 21 months, RubberSource every 3 weeks. The most recent releases landed on September 16, 2026 and September 30, 2026 respectively.

## The numbers

| Metric | E4 Flex | RubberSource |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/e4-flex/id1593079643/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 21 months | **Every 3 weeks** |
| Monetization | Free | — |
| Size | 1 MB | 23 MB |
| Requires iOS | 13.1 | **12.3** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Paul Hamel](https://appshunter.io/developer/1593079645) | [Avanaire Design, LLC](https://appshunter.io/developer/409628132) |

## What reviewers say

### E4 Flex

[App page](https://appshunter.io/ios/app/e4-flex/id1593079643)

This app enables field technicians to connect to and manage E4 Flex readers via Bluetooth Low Energy. It allows for sending commands and receiving responses, facilitating configuration and testing of the readers.

**Highlights:** Connect to E4 Flex readers via BLE, Send commands to readers, Receive responses from readers, Configure E4 Flex readers, Test E4 Flex readers

**In-app purchases:** none


### RubberSource

[App page](https://appshunter.io/ios/app/rubbersource/id6455788482)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is E4 Flex free?

E4 Flex is free to download, with no in-app purchases.

### Is RubberSource free?

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

### Do E4 Flex or RubberSource have ads?

Neither E4 Flex nor RubberSource shows ads.

### Which is updated more often, E4 Flex or RubberSource?

E4 Flex ships an update every 21 months, and RubberSource every 3 weeks. Most recently, E4 Flex was updated on September 16, 2026 and RubberSource on September 30, 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.*