# CHALLNA vs Atto

The clearest difference is in-app purchases: CHALLNA at none against Atto's 1. CHALLNA also leads on ads (none vs shown). Atto's advantage is update cadence (every 4 days vs every 2 weeks). On price, review sentiment, device support and iOS requirement there is nothing between them.

Both are free to download. Atto sells 1 one-off in-app purchase. CHALLNA asks for nothing beyond the download.

CHALLNA ships an update every 2 weeks, Atto every 4 days. The most recent releases landed on October 31, 2026 and November 4, 2026 respectively.

## The numbers

| Metric | CHALLNA | Atto |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 2 weeks | **Every 4 days** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 38 MB | 11 MB |
| Requires iOS | **16.6** | 17.0 |
| Devices | **iPhone, iPad** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [RYNYUL](https://appshunter.io/developer/580531175) | [Beomjin In](https://appshunter.io/developer/1791890813) |

## What reviewers say

### CHALLNA

[App page](https://appshunter.io/ios/app/challna-precise-server-clock/id6759583731)

This app helps you achieve precise timing for critical online events by displaying accurate server time, accounting for network latency. It offers one-touch presets for popular sites, countdown timers, and practice modes to improve your reaction speed for ticket sales, course registrations, and limited drops.

**Highlights:** Millisecond precision synchronization, One-touch server presets, Intuitive countdown timers, Click practice mode, Smart reminders and schedule registration, Direct site access, Dynamic Island support

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

**In-app purchases:** none


### Atto

[App page](https://appshunter.io/ios/app/atto-ticket-drop-timer/id6811104130)

This utility app precisely measures and displays server clock times for time-sensitive events like ticket drops. It offers advanced features to correct for device drift and ensure accurate countdowns, even while using other applications.

**Highlights:** Server clock synchronization, Millisecond precision countdown, Device drift correction, Picture-in-Picture mode, Haptic and sound alerts, Practice mode for timing, Supports over 300 time sources

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Atto Pro | $1.99 | one-time |


## Frequently asked questions

### Is CHALLNA free?

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

### Is Atto free?

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

### Do CHALLNA or Atto have ads?

Atto shows ads; CHALLNA does not.

### Which is updated more often, CHALLNA or Atto?

CHALLNA ships an update every 2 weeks, and Atto every 4 days. Most recently, CHALLNA was updated on October 31, 2026 and Atto on November 4, 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.*