# Timer 555 Calculator Pro vs COLOP Verification App

The clearest difference is price: COLOP Verification App at Free against Timer 555 Calculator Pro's $0.99. COLOP Verification App also leads on update cadence (every 6 weeks vs every 3 months). On ads, in-app purchases, device support and iOS requirement there is nothing between them.

COLOP Verification App is free to download; Timer 555 Calculator Pro costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Timer 555 Calculator Pro ships an update every 3 months, COLOP Verification App every 6 weeks. The most recent releases landed on October 23, 2026 and October 11, 2026 respectively.

## The numbers

| Metric | Timer 555 Calculator Pro | COLOP Verification App |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | **[4.7 (3 ratings)](https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125/reviews)** | — |
| Number of ratings | **3** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Every 6 weeks** |
| Monetization | Paid | — |
| Size | 3 MB | 11 MB |
| Requires iOS | 13.2 | **13.1** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [Colop Digital GmbH](https://appshunter.io/developer/1597279120) |

## What reviewers say

### Timer 555 Calculator Pro

[App page](https://appshunter.io/ios/app/timer-555-calculator-pro/id833443125)

Calculate parameters for monostable and astable circuits. Find component combinations for desired pulse width or frequency. Share circuit files via iCloud Drive or AirDrop.

**Highlights:** Calculate monostable pulse width, Calculate astable frequency, Find component combinations, Adjust component tolerance, Unlimited combinations (Pro), Share circuit files

**In-app purchases:** none


### COLOP Verification App

[App page](https://appshunter.io/ios/app/colop-verification-app/id1543142521)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Timer 555 Calculator Pro free?

Timer 555 Calculator Pro costs $0.99, with no in-app purchases.

### Is COLOP Verification App free?

COLOP Verification App is free to download, with no in-app purchases.

### Do Timer 555 Calculator Pro or COLOP Verification App have ads?

Neither Timer 555 Calculator Pro nor COLOP Verification App shows ads.

### Which is updated more often, Timer 555 Calculator Pro or COLOP Verification App?

Timer 555 Calculator Pro ships an update every 3 months, and COLOP Verification App every 6 weeks. Most recently, Timer 555 Calculator Pro was updated on October 23, 2026 and COLOP Verification App 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.*