# i vs Si

The clearest difference is iOS requirement: Si at 12 against i's 15.6. 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.

i ships an update every 2 months, Si monthly. The most recent releases landed on October 9, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | i | Si |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[3.0 (2 ratings)](https://appshunter.io/ios/app/si-ca-mobileapp/id1471645951/reviews)** |
| Number of ratings | — | **2** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Monthly** |
| Monetization | — | Free |
| Size | 61 MB | 94 MB |
| Requires iOS | 15.6 | **12** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [LIJE TECHNOLOGIES](https://appshunter.io/developer/1295714651) | [SAUERMANN INDUSTRIE](https://appshunter.io/developer/1169513729) |

## What reviewers say

### i

[App page](https://appshunter.io/ios/app/i-topo/id1295714652)

**Features:** macOS Compatibility

**In-app purchases:** none


### Si

[App page](https://appshunter.io/ios/app/si-ca-mobileapp/id1471645951)

Remotely control and interact with specific combustion gas analyzers via Bluetooth. View real-time data, save measurements, and generate reports in various formats directly from your mobile device.

**Highlights:** Bluetooth connectivity, Real-time data viewing, Save measurements, Generate reports (CSV, PDF, XML), Email reports, Remote control

**In-app purchases:** none


## Frequently asked questions

### Is i free?

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

### Is Si free?

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

### Do i or Si have ads?

Neither i nor Si shows ads.

### Which is updated more often, i or Si?

i ships an update every 2 months, and Si monthly. Most recently, i was updated on October 9, 2026 and Si on October 14, 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.*