# Proto.io vs Principle Mirror

The clearest difference is rating: Principle Mirror at 4.2 against Proto.io's 3.7. On price, review sentiment, ratings volume and update cadence there is nothing between them.

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

Principle Mirror holds the better App Store score, 4.2 against 3.7. Both are backed by a comparable volume of ratings — 6 and 14 respectively. Written reviews point the same way: 42% of Proto.io's written reviews are positive against 45% of Principle Mirror's.

Proto.io ships an update every 4 months, Principle Mirror every 2 months. The most recent releases landed on October 23, 2026 and October 29, 2026 respectively.

## The numbers

| Metric | Proto.io | Principle Mirror |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.7 (6 ratings)](https://appshunter.io/ios/app/protoio/id854504039/reviews) | **[4.2 (14 ratings)](https://appshunter.io/ios/app/principle-mirror/id991911319/reviews)** |
| Number of ratings | 6 | **14** |
| Positive reviews | 41.9% of reviews | **45.2% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 months** |
| Monetization | Free | Free |
| Size | 34 MB | 1 MB |
| Requires iOS | **10.0** | 11.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Proto.io](https://appshunter.io/developer/854504042) | [Daniel Hooper](https://appshunter.io/developer/419502228) |

## What reviewers say

### Proto.io

[App page](https://appshunter.io/ios/app/protoio/id854504039)

This application allows users to preview and interact with their Proto.io projects on any device. It supports native touch gestures for a realistic prototyping experience and offers offline viewing of cached projects. Users can also record and share their prototype interactions.

**Highlights:** Preview shared Proto.io projects, Access all projects from your account, Full-screen prototype viewing, Interact with native touch gestures, Preview on any device/screen size, Offline viewing of cached projects, Record and share prototype interactions

**Features:** macOS Compatibility

**In-app purchases:** none

**What reviewers like**

- 👍 Easy to use for prototyping
- 🚀 Powerful features for prototyping
- 💡 Makes prototyping simple and quick
- ✨ Responsive and easy to use prototype
- 🔄 Live updates from computer to phone

**What reviewers complain about**

- 🐛 Can't login
- 🐛 Difficult to delete account
- 🐛 Share link issues
- 🐛 Login issues
- 🐛 Bad app

**Reported bugs**

- Can't login
- Difficult to delete account
- Share link issues
- Login issues
- Cannot sign up or sign in

**Requested features**

- Update UI elements for iOS 13
- Caching projects
- Optimise application for iPhone 6 screen
- Easily switch between accounts like Tweetbot


### Principle Mirror

[App page](https://appshunter.io/ios/app/principle-mirror/id991911319)

Design interactive user interfaces with this companion app for a popular Mac design tool. Seamlessly open Principle files or mirror your Mac's design work directly to your device.

**Highlights:** Open Principle files, Mirror Principle for Mac, Interactive UI design, Companion app functionality

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Proto.io free?

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

### Is Principle Mirror free?

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

### Which has better reviews, Proto.io or Principle Mirror?

Principle Mirror is rated higher. Proto.io averages 3.7 out of 5 from 6 ratings, while Principle Mirror averages 4.2 from 14 ratings.

### Do Proto.io or Principle Mirror have ads?

Neither Proto.io nor Principle Mirror shows ads.

### Which is updated more often, Proto.io or Principle Mirror?

Proto.io ships an update every 4 months, and Principle Mirror every 2 months. Most recently, Proto.io was updated on October 23, 2026 and Principle Mirror on October 29, 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.*