# HydroCloud vs Castly

The clearest difference is in-app purchases: HydroCloud at none against Castly's 2. HydroCloud also leads on iOS requirement (15.0 vs 18.0). Castly's advantage is update cadence (weekly vs monthly). 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. HydroCloud asks for nothing beyond the download.

HydroCloud ships an update monthly, Castly weekly. The most recent releases landed on October 28, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | HydroCloud | Castly |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Monthly | **Weekly** |
| Size | 44 MB | 29 MB |
| Requires iOS | **15.0** | 18.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 12+ |
| Developer | [Beijing Heipitai Technology Co., Ltd](https://appshunter.io/developer/1883620649) | [SlothEase](https://appshunter.io/developer/1816632091) |

## What reviewers say

### HydroCloud

[App page](https://appshunter.io/ios/app/hydrocloud/id6760281837)

**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 HydroCloud free?

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

### Is Castly free?

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

### Do HydroCloud or Castly have ads?

Neither HydroCloud nor Castly shows ads.

### Which is updated more often, HydroCloud or Castly?

HydroCloud ships an update monthly, and Castly weekly. Most recently, HydroCloud was updated on October 28, 2026 and Castly on October 31, 2026.

---

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