# 注册计量师真题库 vs Castly

The clearest difference is in-app purchases: 注册计量师真题库 at none against Castly's 2. 注册计量师真题库 also leads on iOS requirement (13.0 vs 18.0). Castly's advantage is update cadence (weekly vs every 12 months). On price, ads and device support there is nothing between them.

Both are free to download. Castly sells 2 in-app purchases, starting at $9.99 per month. 注册计量师真题库 asks for nothing beyond the download.

注册计量师真题库 ships an update every 12 months, Castly weekly. The most recent releases landed on October 9, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | 注册计量师真题库 | Castly |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 12 months | **Weekly** |
| Monetization | Free with in-app purchases | — |
| Size | 56 MB | 29 MB |
| Requires iOS | **13.0** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 12+ |
| Developer | [将军 黄](https://appshunter.io/developer/1745234400) | [SlothEase](https://appshunter.io/developer/1816632091) |

## What reviewers say

### 注册计量师真题库

[App page](https://appshunter.io/ios/app/2025/id6738836183)

This app provides practice questions and mock exams for the Registered Metrologist qualification exam. It covers exam syllabi and official textbooks, offering daily exercises, topic-specific practice, and simulated test environments to help candidates prepare effectively.

**Highlights:** Daily practice tests, Topic-specific exercises, Past exam papers, Mock exam simulations, Exam syllabus coverage

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### Castly

[App page](https://appshunter.io/ios/app/castly-ai-audiobook-reader/id6768542554)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Castly Pro Monthly | $9.99 | per month |
| Castly Pro Annual | $49.99 | per year |


## Frequently asked questions

### Is 注册计量师真题库 free?

注册计量师真题库 is free to download, with no in-app purchases.

### Is Castly free?

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

### Do 注册计量师真题库 or Castly have ads?

Neither 注册计量师真题库 nor Castly shows ads.

### Which is updated more often, 注册计量师真题库 or Castly?

注册计量师真题库 ships an update every 12 months, and Castly weekly. Most recently, 注册计量师真题库 was updated on October 9, 2026 and Castly on October 31, 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.*