# ZT vs Sirius

The clearest difference is rating: ZT at 4.6 against Sirius's 2.6. ZT also leads on ratings volume (303 vs 5) and iOS requirement (12.0 vs 15.0). Sirius's advantage is review sentiment (60% vs 18%) and update cadence (every 9 days vs every 3 weeks). On price, ads, in-app purchases and monetization model there is nothing between them.

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

ZT holds the better App Store score, 4.6 against 2.6. That said, the two scores are not equally well evidenced: ZT has 303 ratings behind it against 5, so its average is the more settled of the two. Written reviews complicate that: 18% of ZT's written reviews are positive against 60% of Sirius's, so the app with the better star average is not the one people write more warmly about.

ZT ships an update every 3 weeks, Sirius every 9 days. The most recent releases landed on November 13, 2026 and November 12, 2026 respectively.

## The numbers

| Metric | ZT | Sirius |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (303 ratings)](https://appshunter.io/ios/app/zt/id1214656147/reviews)** | [2.6 (5 ratings)](https://appshunter.io/ios/app/sirius-educational-environment/id6748412908/reviews) |
| Number of ratings | **303** | 5 |
| Positive reviews | 18.5% of reviews | **60.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Every 9 days** |
| Monetization | Free | Free |
| Size | 121 MB | 206 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [ZTK, OOO](https://appshunter.io/developer/1577726159) | [AISA IT-SERVICE, AO](https://appshunter.io/developer/1660229310) |

## What reviewers say

### ZT

[App page](https://appshunter.io/ios/app/zt/id1214656147)

Connect with incarcerated individuals through a comprehensive mobile service. Send letters, photos, make audio/video calls, and transfer funds. Offers entertainment options like puzzles and games to enrich communication.

**Highlights:** Send electronic letters and photos, Make audio and video calls, Transfer money to inmate accounts, Add puzzles and games to letters, Instant printing at correctional facilities

**Features:** Vision Pro support

**In-app purchases:** none


### Sirius

[App page](https://appshunter.io/ios/app/sirius-educational-environment/id6748412908)

This app serves as a unified digital platform for residents and guests of a specific region. It consolidates essential services, including a digital profile, event calendar, exclusive bonuses, and news, all accessible from a mobile device. Users can stay informed about events, register for activities, and gain entry using a personal QR code.

**Highlights:** Digital resident and guest profile, Event calendar and registration, Personal QR code for entry and bonuses, Exclusive partner discounts and promotions, Unified digital space for regional services, News and updates

**In-app purchases:** none


## Frequently asked questions

### Is ZT free?

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

### Is Sirius free?

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

### Which has better reviews, ZT or Sirius?

ZT is rated higher. ZT averages 4.6 out of 5 from 303 ratings, while Sirius averages 2.6 from 5 ratings.

### Do ZT or Sirius have ads?

Neither ZT nor Sirius shows ads.

### Which is updated more often, ZT or Sirius?

ZT ships an update every 3 weeks, and Sirius every 9 days. Most recently, ZT was updated on November 13, 2026 and Sirius on November 12, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*