# Calki vs MainframeMonitor

The clearest difference is in-app purchases: MainframeMonitor at none against Calki's 3. MainframeMonitor also leads on ads (none vs shown) and rating (5.0 vs 4.8). Calki's advantage is ratings volume (16 vs 1). On price, update cadence, device support and iOS requirement there is nothing between them.

Both are free to download. Calki sells 3 in-app purchases, starting at $0.99 per month. MainframeMonitor asks for nothing beyond the download.

MainframeMonitor holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: Calki has 16 ratings behind it against 1, so its average is the more settled of the two.

Both ship on a similar rhythm, roughly fortnightly. The most recent releases landed on October 25, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Calki | MainframeMonitor |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.8 (16 ratings)](https://appshunter.io/ios/app/calki-scanner-calculator/id6747059181/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/mainframemonitor/id6809454680/reviews)** |
| Number of ratings | **16** | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Fortnightly | Fortnightly |
| Monetization | Ad-supported | **Free** |
| Size | 52 MB | 24 MB |
| Requires iOS | 18.0 | **17.0** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Vimal Parthan](https://appshunter.io/developer/1819662283) | [Ralf Langhoff](https://appshunter.io/developer/1706183785) |

## What reviewers say

### Calki

[App page](https://appshunter.io/ios/app/calki-scanner-calculator/id6747059181)

This app combines a powerful camera number scanner, a full-featured unit converter, and a beautifully designed calculator. It allows you to scan numbers from documents, convert units across various categories, and perform calculations with live previews and advanced history.

**Highlights:** Camera number scanner (OCR), Unit converter with 12 categories, Smart calculator with live preview, Advanced calculation history, Customizable themes and fonts, Ad-free experience

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Calki Pro Monthly | $0.99 | per month |
| Calki Pro Yearly | $2.99 | per year |
| Calki Pro Lifetime | $5.99 | one-time |


### MainframeMonitor

[App page](https://appshunter.io/ios/app/mainframemonitor/id6809454680)

Transform your iPhone into a vintage mainframe with a nostalgic CRT display. Monitor live system stats like battery, CPU, and memory, all within an authentic retro console experience. Includes hidden classic text-based games.

**Highlights:** Live system monitoring (battery, CPU, memory, storage), Home screen widgets, Authentic CRT effects (glow, scanlines), Retro boot sequence, Hidden classic text-based games, Customizable color themes (Green, Amber)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Calki free?

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

### Is MainframeMonitor free?

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

### Which has better reviews, Calki or MainframeMonitor?

MainframeMonitor is rated higher. Calki averages 4.8 out of 5 from 16 ratings, while MainframeMonitor averages 5.0 from 1 ratings.

### Do Calki or MainframeMonitor have ads?

Calki shows ads; MainframeMonitor does not.

### Which is updated more often, Calki or MainframeMonitor?

Calki ships an update fortnightly, and MainframeMonitor fortnightly. Most recently, Calki was updated on October 25, 2026 and MainframeMonitor on October 24, 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.*