TrueNTP

Measure how far your phone's clock has drifted from true time. Cross-checks several time servers, gives you a near perfect reference for offline and air-gapped systems.

TrueNTP measures how far your phone's clock is from true time.

It queries multiple independent time servers, cross-checks their answers, and computes a corrected time with millisecond precision. You see the corrected time, your device clock's drift, and an uncertainty figure so you know how much to trust the number.

WHO IT'S FOR Network admins verifying NTP infrastructure. Cell techs checking tower timing. Sysadmins chasing certificate and Kerberos clock-skew errors. IT teams resyncing air-gapped and offline systems: hold the phone next to the console and set the clock from a known-good reference. And anyone curious what time it actually is.

HOW IT MEASURES • Bursts of SNTP samples to every active server, weighted by network quality (1/RTT) • Per-server offset, round-trip time, and stratum at a glance • Optional outlier rejection against the cross-server median • Six curated presets (Apple, Cloudflare, NIST, Google, Microsoft, Amazon). Enable any of them or add your own • An uncertainty readout alongside every measurement

WHAT YOU SEE • A large clock showing corrected time, ticking smoothly, unaffected by OS clock changes • Device clock card: your clock's drift, labeled plainly as DEVICE AHEAD, DEVICE BEHIND, or IN SYNC • Server list with per-server detail sheets: refid, root delay, root dispersion, per-sample scatter • 30-minute offset timeline showing your clock's behavior

PRIVACY No accounts, no analytics, no tracking. Settings and history stay on your device. The privacy policy is one page.

A short, plain-language NTP guide is included.