# Piazza vs Armillary Sphere

The clearest difference is review sentiment: Armillary Sphere at 86% against Piazza's 14%. Armillary Sphere also leads on rating (4.0 vs 2.1) and iOS requirement (9.0 vs 15.6). Piazza's advantage is update cadence (every 11 days vs every 5 months) and ratings volume (279 vs 6). 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.

Armillary Sphere holds the better App Store score, 4.0 against 2.1. That said, the two scores are not equally well evidenced: Piazza has 279 ratings behind it against 6, so its average is the more settled of the two. Written reviews point the same way: 14% of Piazza's written reviews are positive against 86% of Armillary Sphere's.

Piazza ships an update every 11 days, Armillary Sphere every 5 months. The most recent releases landed on October 14, 2026 and October 5, 2026 respectively.

## The numbers

| Metric | Piazza | Armillary Sphere |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [2.1 (279 ratings)](https://appshunter.io/ios/app/piazza/id453142230/reviews) | **[4.0 (6 ratings)](https://appshunter.io/ios/app/armillary-sphere/id1225026601/reviews)** |
| Number of ratings | **279** | 6 |
| Positive reviews | 14.2% of reviews | **85.7% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 11 days** | Every 5 months |
| Monetization | Free | Free |
| Size | 3 MB | 275 MB |
| Requires iOS | 15.6 | **9.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Piazza Technologies, Inc.](https://appshunter.io/developer/453142233) | [HKU TELI](https://appshunter.io/developer/1153931100) |

## What reviewers say

### Piazza

[App page](https://appshunter.io/ios/app/piazza/id453142230)

This platform facilitates communication and learning for higher education. Students can ask and answer questions, while instructors can monitor student engagement. It provides real-time updates and a centralized space for class interactions.

**Highlights:** Ask and answer questions, Real-time updates, Centralized class communication, Student engagement monitoring, Mobile access for students and instructors

**In-app purchases:** none

**What reviewers like**

- 🚀 Useful app
- 🚀 Great for tracking classes
- 🚀 Convenient mobile access

**What reviewers complain about**

- 🐛 Crashes frequently
- 🐛 Buggy and unreliable
- 🐛 Lacks key features from web version
- 🐛 Poor user interface and navigation
- 🔒 Login and authentication issues

**Reported bugs**

- Inability to post or reply
- Randomly logs out users
- Fails to load posts and resources
- Incompatible with newer iOS versions

**Requested features**

- Dark mode option
- Ability to access course materials
- Improved formatting and editing tools
- Better organization of posts and discussions
- Seamless integration with web version


### Armillary Sphere

[App page](https://appshunter.io/ios/app/armillary-sphere/id1225026601)

Explore the cosmos with this 3D astronomical tool. Measure and record the positions and movements of celestial bodies, and determine sunrise/sunset times and day length. Reconstructs an ancient scientific instrument using modern technology.

**Highlights:** 3D astronomical model, Measure celestial positions, Record Sun and star movements, Determine sunrise/sunset times, Calculate day length, Adjustable Meridian, Equator, Horizon, Ecliptic, Altitude

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Piazza free?

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

### Is Armillary Sphere free?

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

### Which has better reviews, Piazza or Armillary Sphere?

Armillary Sphere is rated higher. Piazza averages 2.1 out of 5 from 279 ratings, while Armillary Sphere averages 4.0 from 6 ratings.

### Do Piazza or Armillary Sphere have ads?

Neither Piazza nor Armillary Sphere shows ads.

### Which is updated more often, Piazza or Armillary Sphere?

Piazza ships an update every 11 days, and Armillary Sphere every 5 months. Most recently, Piazza was updated on October 14, 2026 and Armillary Sphere on October 5, 2026.

---

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