# KOEL iGreen vs First Calling App

The clearest difference is iOS requirement: First Calling App at 15.0 against KOEL iGreen's 18.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Both ship on a similar rhythm, roughly monthly. The most recent releases landed on September 25, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | KOEL iGreen | First Calling App |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Monthly | Monthly |
| Monetization | Free | — |
| Size | 24 MB | 30 MB |
| Requires iOS | 18.0 | **15.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 17+ | 4+ |
| Developer | [Tor.ai Limited](https://appshunter.io/developer/1288507527) | [ROSHVEER SERVICES PRIVATE LIMITED](https://appshunter.io/developer/1885209219) |

## What reviewers say

### KOEL iGreen

[App page](https://appshunter.io/ios/app/koel-igreen/id1481347446)

Monitor machine health, receive critical alarms, and manage preventive maintenance schedules. This app works with a 'Plug and Play' device that connects directly to your machine's harness for real-time data.

**Highlights:** Machine health performance monitoring, Machine alarms and trips alerts, Preventive maintenance scheduling, Plug and Play device integration, Real-time data monitoring

**Features:** macOS Compatibility

**In-app purchases:** none


### First Calling App

[App page](https://appshunter.io/ios/app/first-calling-app/id6760596159)

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

**In-app purchases:** none


## Frequently asked questions

### Is KOEL iGreen free?

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

### Is First Calling App free?

First Calling App is free to download, with no in-app purchases.

### Do KOEL iGreen or First Calling App have ads?

Neither KOEL iGreen nor First Calling App shows ads.

### Which is updated more often, KOEL iGreen or First Calling App?

KOEL iGreen ships an update monthly, and First Calling App monthly. Most recently, KOEL iGreen was updated on September 25, 2026 and First Calling App 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.*