# BlueGrays vs 555 Timer & Oscillators Pro

The clearest difference is price: BlueGrays at Free against 555 Timer & Oscillators Pro's $4.99. BlueGrays also leads on update cadence (every 6 days vs every 3 months). 555 Timer & Oscillators Pro's advantage is in-app purchases (none vs 6) and ads (none vs shown). On device support and iOS requirement there is nothing between them.

BlueGrays is free to download; 555 Timer & Oscillators Pro costs $4.99 up front. BlueGrays sells 6 in-app purchases, starting at $2.99 per month. 555 Timer & Oscillators Pro asks for nothing beyond the download.

BlueGrays ships an update every 6 days, 555 Timer & Oscillators Pro every 3 months. The most recent releases landed on September 17, 2026 and September 24, 2026 respectively.

## The numbers

| Metric | BlueGrays | 555 Timer & Oscillators Pro |
| --- | --- | --- |
| Price | **Free** | $4.99 |
| Rating | **[4.4 (11 ratings)](https://appshunter.io/ios/app/bluegrays-learn-electronics/id6502332602/reviews)** | — |
| Number of ratings | **11** | — |
| Positive reviews | 64.3% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 6 days** | Every 3 months |
| Monetization | Free with in-app purchases | — |
| Size | 51 MB | 22 MB |
| Requires iOS | **15.1** | 16.0 |
| Devices | iPhone, iPod | **iPhone, iPad, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Yunus Emre Eke](https://appshunter.io/developer/1713998736) | [ALG Software Lab](https://appshunter.io/developer/1650561236) |

## What reviewers say

### BlueGrays

[App page](https://appshunter.io/ios/app/bluegrays-learn-electronics/id6502332602)

Learn electronics with interactive projects, a component catalog, and personal inventory management. Start with free projects and unlock full access to Arduino, ESP32, and IoT content with a premium subscription. Gamified learning with badges and levels keeps you motivated.

**Highlights:** Free starter projects, Unlimited Arduino/ESP32/IoT projects, Detailed circuit diagrams and code, Component catalog with specifications, Personal inventory management, Gamified learning with badges and levels, Multi-language support

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

**In-app purchases (6)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium (Monthly) | $2.99 | per month |
| Premium (Yearly) | $11.99 | per year |
| 5x Aylık Eğitimci Paketi | $12.99 | one-time |
| 10x Aylık Eğitimci Paketi | $23.99 | one-time |
| 5x Yıllık Eğitimci Paketi | $53.99 | one-time |
| 10x Yıllık Eğitimci Paketi | $101.99 | one-time |


### 555 Timer & Oscillators Pro

[App page](https://appshunter.io/ios/app/555-timer-and-oscillators-pro/id6504415162)

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is BlueGrays free?

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

### Is 555 Timer & Oscillators Pro free?

555 Timer & Oscillators Pro costs $4.99, with no in-app purchases.

### Do BlueGrays or 555 Timer & Oscillators Pro have ads?

BlueGrays shows ads; 555 Timer & Oscillators Pro does not.

### Which is updated more often, BlueGrays or 555 Timer & Oscillators Pro?

BlueGrays ships an update every 6 days, and 555 Timer & Oscillators Pro every 3 months. Most recently, BlueGrays was updated on September 17, 2026 and 555 Timer & Oscillators Pro on September 24, 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.*