# Bói Bài vs OTOTETSU

The clearest difference is review sentiment: OTOTETSU at 93% against Bói Bài's 0%. OTOTETSU also leads on price (Free vs $1.99) and update cadence (every 2 months vs every 85 months). Bói Bài's advantage is iOS requirement (12.0 vs 15.0). On ads, in-app purchases and device support there is nothing between them.

OTOTETSU is free to download; Bói Bài costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Bói Bài ships an update every 85 months, OTOTETSU every 2 months. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Bói Bài | OTOTETSU |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Rating | — | **[4.7 (19 ratings)](https://appshunter.io/ios/app/ototetsu/id1557885726/reviews)** |
| Number of ratings | — | **19** |
| Positive reviews | 0.0% of reviews | **93.1% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 85 months | **Every 2 months** |
| Monetization | Paid | **Free** |
| Size | 49 MB | 20 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [DOTDAC VIET NAM COMPANY LIMITED](https://appshunter.io/developer/1824573388) | [Hisato Takeuchi](https://appshunter.io/developer/1512764876) |

## What reviewers say

### Bói Bài

[App page](https://appshunter.io/ios/app/boi-bai/id452497784)

Discover daily fortunes and future insights using a standard deck of cards. Explore two divination methods: daily readings and ancestral guidance. Uncover the mysteries held within the cards.

**Highlights:** Daily fortune telling, Ancestral guidance readings, Card-based divination, Future insights, Mysteries of the cards

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

**In-app purchases:** none


### OTOTETSU

[App page](https://appshunter.io/ios/app/ototetsu/id1557885726)

This app simulates the characteristic sounds of electric trains, generated by inverters controlling motor torque and speed. Users can design sounds for imaginary trains by manipulating waveforms and motor sounds.

**Highlights:** Simulates electric train acceleration/deceleration sounds, Generates waveforms from inverters, Simulates motor sounds, Design imaginary train sounds, Customize torque and rotational speed effects

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

**In-app purchases:** none


## Frequently asked questions

### Is Bói Bài free?

Bói Bài costs $1.99, with no in-app purchases.

### Is OTOTETSU free?

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

### Do Bói Bài or OTOTETSU have ads?

Neither Bói Bài nor OTOTETSU shows ads.

### Which is updated more often, Bói Bài or OTOTETSU?

Bói Bài ships an update every 85 months, and OTOTETSU every 2 months. Most recently, Bói Bài was updated on November 1, 2026 and OTOTETSU on November 3, 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.*