Second vs One
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Second
This utility app provides precise server time synchronization down to milliseconds, ideal for critical moments like course registration or ticketing. It features drift tracking for sustained accuracy and a Picture-in-Picture timer for live monitoring while using other applications.
- Precise server time synchronization
- Drift tracking for sustained accuracy
- Picture-in-Picture timer
- Example site shortcuts
- Multilingual support
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Precise server time, at a glance. Second-Sync is a time synchronization tool for moments where one second matters, such as course registration and ticketing. It multi-samples the HTTP Date of your chosen site and aligns the difference from the server clock down to milliseconds. Drift tracking maintains accuracy over time, while the PiP timer lets you watch live server time even when using other apps. Key features - Precise synchronization: collects HTTP Date in parallel at least 30 times, then calculates the offset after RTT compensation, outlier removal, and EMA smoothing. - Drift estimation: runs linear regression on measured samples to track the slope of the device clock and maintain accuracy as time passes. - PiP timer: opens a Picture in Picture timer as a companion app, so you can monitor the server clock live while using a browser or other apps. - Example site shortcuts: quick buttons to load course registration pages for major Korean universities and ticket booking sites. - Multilingual support: supports Korean, English, Japanese, and Simplified Chinese, with a separate in-app language setting. Recommended for - Anyone who wants exact server time in situations where it is critical, such as registration, ticketing, or reservations. - Anyone who wants to keep accurate server time visible on iPhone or iPad while booking on the go. Notes - Synchronization may fail on sites that do not support the HTTP Date header. If so, enter another target server or use the example sites in the app. - Picture in Picture works only on supported devices running iOS 15 or later, including iPadOS. - Sync your server time with Second-Sync now. One button gives you stable synchronization and a PiP timer, so you do not miss the important moment!
One
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Scan your paper documents, receipts, notes and IDs and turn them into high‑quality digital files with one tap. -Smart document edge detection: Automatically recognize document borders, you can also manually adjust crop area and fix skewed documents. -Multiple export formats: Export scans as PDF or image files for saving, sharing and printing. -OCR Text Recognition: Extract text from scanned documents and turn paper copies into editable text. -File management: Create and rename custom folders to organize your scanned files efficiently. Digitize receipts, contracts, notes, ID cards and books easily. Go paper‑free and manage your documents anywhere.
Screenshots
Verdict
The clearest difference is ads: One at none against Second's shown. Second's advantage is device support (3 vs 1) and iOS requirement (15.6 vs 17.0). On price and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Second sells 1 one-off in-app purchase and One sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.
| Parameter | Second | One |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (4 ratings) — better | — |
| Positive reviews | 88.9% of reviews | — |
| Number of ratings | 4 — better | — |
| Update frequency | Every 2 days | — |
| Ads | Yes | No — better |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 15.6 — better | 17.0 |
| Further details — not scored | ||
| Size | 69 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Minjun Kim | 忠政 衣 |
In-app purchases
Second
- 초정확 Pro 업그레이드$1.99
One
- Lifetime Member$9.99









