# Graycode vs 专利大王

The clearest difference is price: 专利大王 at Free against Graycode's $2.99. 专利大王 also leads on update cadence (every 5 weeks vs every 10 months). Graycode's advantage is in-app purchases (none vs 5) and ads (none vs shown). On device support and iOS requirement there is nothing between them.

专利大王 is free to download; Graycode costs $2.99 up front. 专利大王 sells 5 one-off in-app purchases. Graycode asks for nothing beyond the download.

Graycode ships an update every 10 months, 专利大王 every 5 weeks. The most recent releases landed on October 11, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | Graycode | 专利大王 |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | **[3.0 (2 ratings)](https://appshunter.io/ios/app/graycode/id548428653/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 66.7% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 10 months | **Every 5 weeks** |
| Monetization | Paid | — |
| Size | 2 MB | 36 MB |
| Requires iOS | 12.0 | 12.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Duo Pisceses, Inc.](https://appshunter.io/developer/850707063) | [BEIJING INCOIDEA CO.LTD](https://appshunter.io/developer/1262262808) |

## What reviewers say

### Graycode

[App page](https://appshunter.io/ios/app/graycode/id548428653)

This utility converts numbers between decimal, hexadecimal, binary, and Gray code formats. Changes to one value automatically update the others, making it a convenient tool for engineers. It also features an animated demonstration of the Tower of Hanoi puzzle.

**Highlights:** Decimal, hex, binary, Gray code conversion, Real-time updates, Handy calculator for engineers, Animated Tower of Hanoi solution, Supports iPhone, iPad, iPod

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

**In-app purchases:** none


### 专利大王

[App page](https://appshunter.io/ios/app/id1091971568)

**Features:** macOS Compatibility

**In-app purchases (5)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 专利大王VIP月卡 | $8.99 | one-time |
| 专利大王VIP季卡 | $19.99 | one-time |
| 专利大王VIP半年卡 | $34.99 | one-time |
| 专利大王VIP年卡 | $59.99 | one-time |
| 专利大王VIP年费会员 | $64.99 | one-time |


## Frequently asked questions

### Is Graycode free?

Graycode costs $2.99, with no in-app purchases.

### Is 专利大王 free?

专利大王 is free to download, with in-app purchases available.

### Do Graycode or 专利大王 have ads?

专利大王 shows ads; Graycode does not.

### Which is updated more often, Graycode or 专利大王?

Graycode ships an update every 10 months, and 专利大王 every 5 weeks. Most recently, Graycode was updated on October 11, 2026 and 专利大王 on October 6, 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.*