# KOSTAL InverterApp vs TheFlex

The clearest difference is in-app purchases: KOSTAL InverterApp at none against TheFlex's 2. KOSTAL InverterApp also leads on update cadence (every 2 months vs every 6 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. TheFlex sells 2 in-app purchases, starting at $6.99 per month. KOSTAL InverterApp asks for nothing beyond the download.

KOSTAL InverterApp ships an update every 2 months, TheFlex every 6 months. The most recent releases landed on November 2, 2026 and October 27, 2026 respectively.

## The numbers

| Metric | KOSTAL InverterApp | TheFlex |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 6 months |
| Monetization | Free | — |
| Size | 78 MB | 14 MB |
| Requires iOS | 13.0 | 13.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [KOSTAL Industrie Elektrik GmbH](https://appshunter.io/developer/1436479665) | [Flexus AG](https://appshunter.io/developer/723422616) |

## What reviewers say

### KOSTAL InverterApp

[App page](https://appshunter.io/ios/app/kostal-inverterapp/id1436479666)

Access and manage KOSTAL drive controllers with Bluetooth via your smartphone or tablet. Perform diagnostics, commissioning, and parameter settings remotely. Data records are compatible with PC software for seamless workflow.

**Highlights:** Bluetooth connectivity, Wizard-guided commissioning, Save and copy device settings, Send data records via email, Parameter settings in plain text, Control drive controller, Access process variables, Error analysis and history

**Features:** macOS Compatibility

**In-app purchases:** none


### TheFlex

[App page](https://appshunter.io/ios/app/theflex/id1621676862)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| License / Month | $6.99 | per month |
| License / Year | $68.99 | per year |


## Frequently asked questions

### Is KOSTAL InverterApp free?

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

### Is TheFlex free?

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

### Do KOSTAL InverterApp or TheFlex have ads?

Neither KOSTAL InverterApp nor TheFlex shows ads.

### Which is updated more often, KOSTAL InverterApp or TheFlex?

KOSTAL InverterApp ships an update every 2 months, and TheFlex every 6 months. Most recently, KOSTAL InverterApp was updated on November 2, 2026 and TheFlex on October 27, 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.*