# Opamp tools vs 555 Timer & Oscillators Guide

The clearest difference is in-app purchases: 555 Timer & Oscillators Guide at none against Opamp tools's 1. 555 Timer & Oscillators Guide also leads on update cadence (every 5 months vs every 12 months). Opamp tools's advantage is ads (none vs shown) and iOS requirement (12.0 vs 16.0). On price and device support there is nothing between them.

Both are free to download. Opamp tools sells 1 one-off in-app purchase. 555 Timer & Oscillators Guide asks for nothing beyond the download.

Opamp tools ships an update every 12 months, 555 Timer & Oscillators Guide every 5 months. The most recent releases landed on May 16, 2026 and September 24, 2026 respectively.

## The numbers

| Metric | Opamp tools | 555 Timer & Oscillators Guide |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | Every 12 months | **Every 5 months** |
| Size | 4 MB | 24 MB |
| Requires iOS | **12.0** | 16.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | +4 |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [ALG Software Lab](https://appshunter.io/developer/1650561236) |

## What reviewers say

### Opamp tools

[App page](https://appshunter.io/ios/app/opamp-tools/id1616271826)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock pro feature | $1.99 | one-time |


### 555 Timer & Oscillators Guide

[App page](https://appshunter.io/ios/app/555-timer-and-oscillators-guide/id6504487994)

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

**In-app purchases:** none


## Frequently asked questions

### Is Opamp tools free?

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

### Is 555 Timer & Oscillators Guide free?

555 Timer & Oscillators Guide is free to download, with no in-app purchases.

### Do Opamp tools or 555 Timer & Oscillators Guide have ads?

555 Timer & Oscillators Guide shows ads; Opamp tools does not.

### Which is updated more often, Opamp tools or 555 Timer & Oscillators Guide?

Opamp tools ships an update every 12 months, and 555 Timer & Oscillators Guide every 5 months. Most recently, Opamp tools was updated on May 16, 2026 and 555 Timer & Oscillators Guide 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.*