Second-Sync: iPhone vs Android

Precise server time, at a glance.

Second-Sync is a time synchronisation tool for moments where one second matters, such as course enrolment 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 synchronisation: 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 enrolment 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 enrolment, ticketing or reservations.
- Anyone who wants to keep accurate server time visible on iPhone or iPad while booking on the go.

Notes
- Synchronisation 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 synchronisation and a PiP timer, so you do not miss the important moment!

Precise server time, at a glance.

Second-Sync is a time synchronisation tool for moments where one second matters, such as course enrolment 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 synchronisation: 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 enrolment 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 enrolment, ticketing or reservations.
- Anyone who wants to keep accurate server time visible on iPhone or iPad while booking on the go.

Notes
- Synchronisation 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 synchronisation and a PiP timer, so you do not miss the important moment!

Check the accurate server clock at a glance.

Ultra-accurate is a server time timer that measures the HTTP Date of the desired site multiple times and corrects the error with the server clock in milliseconds for moments where every second is important, such as course registration and ticketing. Drift tracking ensures accuracy over time, and PiP Timer lets you keep track of server times while using a browser or other apps.

Main features
- Precise synchronization: HTTP Date is collected multiple times, undergoes RTT correction, outlier removal, and EMA smoothing, then calculates the server time offset.
- Drift estimation: Tracks the drift of a device's clock based on measurement samples to correct for displayed time drift over time.
- PiP Server Time Timer: You can display the server time in the Picture in Picture window and check the time while viewing the course registration, ticketing, and reservation screens.
- Proven site presets: We provide presets that allow you to quickly select major domestic university course registration sites and ticketing/reservation sites.
- Improved site compatibility: By strengthening the HTTPS and Date header processing flow, more sites can reliably check the server time.
- Notification options: Screen notifications and sound notifications can be turned on and off respectively, allowing you to use them according to the situation.
- Multilingual support: Supports Korean, English, Japanese, and Simplified Chinese, and you can select the language within the app.

I recommend it to people like this
- Those who prepare for moments where server time is the standard, such as course registration, ticketing, and reservations.
- Those who want to view accurate server time and perform browser tasks simultaneously on their Android phone or tablet
- Those who always keep track of time using the PiP window and do not want to miss important moments

Precautions
- Synchronization may fail on sites that do not provide the HTTP Date header or have limited network response. In this case, please enter a different synchronization target server or use the app's preset.
- The Picture in Picture feature only works on supported devices such as Android 8.0 or higher.
- Sound notifications may be affected by your device's volume, silent mode, and notification settings.

Set the server time right now with extreme accuracy. Reliable synchronization, PiP timer, and notification options help you better prepare for important moments.