# RainbowStar vs Otto

The clearest difference is update cadence: Otto at every 5 days against RainbowStar's every 5 weeks. RainbowStar's advantage is iOS requirement (12.0 vs 16.0.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. RainbowStar sells 6 one-off in-app purchases and Otto sells 6 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.

RainbowStar ships an update every 5 weeks, Otto every 5 days. Both last shipped on October 11, 2026.

## The numbers

| Metric | RainbowStar | Otto |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 5 weeks | **Every 5 days** |
| Size | 287 MB | 159 MB |
| Requires iOS | **12.0** | 16.0.0 |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, Mac, Apple Watch** |
| Age rating | 4+ | 17+ |
| Developer | [Open Knowledge Association Ltd.](https://appshunter.io/developer/868011308) | [Tom Honey](https://appshunter.io/developer/1782767469) |

## What reviewers say

### RainbowStar

[App page](https://appshunter.io/ios/app/rainbowstar/id1251256553)

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 8個金幣 | $0.99 | one-time |
| 48個金幣 | $5.99 | one-time |
| 98個金幣 | $12.99 | one-time |
| 218個金幣 | $27.99 | one-time |
| 368個金幣 | $46.99 | one-time |
| 688個金幣 | $89.99 | one-time |


### Otto

[App page](https://appshunter.io/ios/app/otto-language-learning/id6738887838)

**Features:** Apple Watch app

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Otto Pro - Monthly | $2.99 | per month |
| Otto Pro - Yearly | $29.99 | per year |
| 20 Tokens | $1.99 | one-time |
| 70 Tokens | $4.99 | one-time |
| 180 Tokens | $9.99 | one-time |
| 450 Tokens | $24.99 | one-time |


## Frequently asked questions

### Is RainbowStar free?

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

### Is Otto free?

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

### Do RainbowStar or Otto have ads?

Neither RainbowStar nor Otto shows ads.

### Which is updated more often, RainbowStar or Otto?

RainbowStar ships an update every 5 weeks, and Otto every 5 days. Most recently, RainbowStar was updated on October 11, 2026 and Otto on October 11, 2026.

---

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