Public UTC

Variants

Choose the leap-second policy that fits your stack. Each variant runs on a dedicated chrony instance with the same privacy guarantees and NTS support. The apex public-utc.com serves this website only — not NTP.

Quick start (Smear, recommended):

server smear.public-utc.com iburst nts

See smear.html or leap.html for full client configuration.

Mission

Public UTC exists to give anyone a fast, private, authenticated source of time — no signup, no tracking, no paywall. We serve plain NTP and NTS-secured NTP on two dedicated subdomains so you can pick the leap-second policy your stack needs, synchronise against an intentionally diverse set of stratum-1 references run by national metrology institutes and military timing labs, and never log client traffic.

The server is operated as a public good: hardware, bandwidth, and time are donated, the configuration is boring on purpose, and the privacy guarantees are structural rather than promised. Everything on this page — the endpoints, the policy, and the operational stack — is documented so anyone can reproduce, audit, or take over the setup if they need to.

Privacy

We do not log NTP client requests. No client data is stored, sold, or shared with third parties.

• No client logging — NTP queries are never written to disk.
• Encrypted storage — all data at rest is protected with ZFS native encryption.
• No shell history — operator sessions leave no command history on the server.
• Headless server — eliminating physical access vectors.
• Operational logs only — the daemon records its own tracking and measurements against upstream references, not client requests.
• No analytics or trackers — this site is static HTML and sets no cookies.

Features

Infrastructure

The system has no remote console exposed to the public internet beyond the services listed above.

Upstream References

An intentionally diverse set of stratum-1 references run by national metrology institutes and military timing labs across multiple jurisdictions. USNO and NIST realise UTC independently; European and Asian institutes contribute further to BIPM's UTC ensemble. No single upstream — and no single country — can shift the served clock.

Troubleshooting

Variant-specific notes are on smear.html and leap.html. General guidance:

• NTS-KE fails — allow outbound TCP 4460; TLS-intercepting middleboxes break NTS.
• Clock far off — bootstrap with plain NTP or set the clock manually before enabling NTS.
• Certificate rejected — set SNI to the variant hostname; wrong system time causes TLS validation failure.
• Mixed variants — do not configure both smear.public-utc.com and leap.public-utc.com on the same host.

FAQ

Acceptable Use

• Use sane polling intervals. chrony and ntpsec defaults are fine.
• Do not hardcode leap.public-utc.com or smear.public-utc.com in shipping consumer products or appliances without contacting us first.
• Do not use the service to amplify or proxy traffic to third parties.
• Abusive sources may be rate-limited or blocked without notice.

Managed Services

Beyond the public time service, we offer managed private NTP and NTS deployments for organisations that need their own controlled time source — regulated environments, exchanges, broadcasters, ISPs, enterprises, and anyone who wants the same operational model on their own infrastructure or hosted by us.

Typical engagements include:

• Dedicated chrony / ntpsec time servers with custom upstream policy and NTS-KE certificates issued for your domain.
• Anycast or multi-site NTP for latency-sensitive deployments.
• Stratum-1 deployments with GNSS / PTP / atomic-clock disciplining.
• Hardened time appliances built on FreeBSD, ZFS, and chrony.
• Bare-metal management — provisioning, OS hardening, monitoring, patching, and on-call response.
• Migration from existing setups (ntpd, w32time) to authenticated NTS.

For pricing and scoping, see Contact.

Sponsors

Public UTC is operated as a public good and runs on volunteer time, donated bandwidth, and out-of-pocket hardware. Sponsorships keep it that way — no ads, no tracking, no paywalled tiers.

Sponsors receive a logo and link on this page for the duration of the sponsorship, with no influence over editorial or operational decisions. If you need operational support, SLAs, or a dedicated time service, see Managed Services instead.

Any contribution helps — there are no fixed amounts and no tiers. Sponsorships can be invoiced (EUR, SEPA / SWIFT) or paid in BTC. To set one up, see Contact.

No sponsors yet.

Legal

Trademarks

All project, institute, and product names referenced on this site — including NIST, USNO, PTB, NPL, METAS, INRIM, NICT, chrony, ntpsec, FreeBSD, ZFS, Linux, Windows, and macOS — are the property of their respective owners. Public UTC is an independent NTP operator and is not affiliated with, endorsed by, or sponsored by any of these organisations unless explicitly stated.

Content

Public UTC distributes time derived from stratum-1 references operated by the institutes listed under Upstream References. We add nothing and modify nothing in the time signal beyond ordinary stratum-2 disciplining and the leap-second policy of the variant you select.

Warranty disclaimer

This service is provided "as is" and "as available", without warranty of any kind, express or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, non-infringement, or uninterrupted availability. Use of this time service is at your own risk.

Limitation of liability

To the maximum extent permitted by applicable law, the operators of Public UTC shall not be liable for any direct, indirect, incidental, consequential, or special damages arising from the use of, or inability to use, this service.

Abuse and takedowns

To report abusive use, contact us via Contact with the source IP(s) and the basis for the request.

Privacy

We do not log individual NTP requests, set cookies, or run analytics. See Privacy for details.

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