Public NTP server · 11 regions · open source

Daylight saving time,
without the jump.

smoothtime spreads the 1-hour DST change smoothly across the entire season, so servers, homelabs and IoT devices never see a sudden clock change.

UTC --:--:--NTP · UDP/123Drift · linear

Official local time

--:--:--

smoothtime

--:--:--

europe-central.smoothtime.io

Get started View on GitHub

How it works

A straight line instead of a step

Official time jumps by one hour twice a year. smoothtime drifts linearly between the two transition dates instead, a fraction of a second per day, and meets official time exactly at each switch.

Official UTC offsetsmoothtime offsetToday

Formula: offset = base + days_passed / total_days between DST end and the next DST start; mirrored during summer.

Regions

Pick the server for your time zone

Offsets update live. Use the server for your region.

Region	Server	smoothtime now	Official now
Europe West WET/WEST	`europe-west.smoothtime.io`	-	-
Europe Central CET/CEST	`europe-central.smoothtime.io`	-	-
Europe East EET/EEST	`europe-east.smoothtime.io`	-	-
US Eastern EST/EDT	`us-eastern.smoothtime.io`	-	-
US Central CST/CDT	`us-central.smoothtime.io`	-	-
US Mountain MST/MDT	`us-mountain.smoothtime.io`	-	-
US Pacific PST/PDT	`us-pacific.smoothtime.io`	-	-
Australia Sydney AEST/AEDT	`australia-sydney.smoothtime.io`	-	-
New Zealand NZST/NZDT	`new-zealand.smoothtime.io`	-	-
Chile CLT/CLST	`chile.smoothtime.io`	-	-
Argentina ART, no DST	`argentina.smoothtime.io`	-	-

Setup

Set up in about 30 seconds

Set your system time zone to UTC. Standard time servers send pure UTC and your computer adds the local time zone. smoothtime already includes your time zone and the smooth DST drift in the time it sends. If you keep your local time zone, the offset is applied twice and your clock will be wrong.

Recommended. Most modern Linux systems use chrony.

sudo timedatectl set-timezone UTC
echo "server europe-central.smoothtime.io iburst" | sudo tee -a /etc/chrony.conf
sudo systemctl restart chronyd

Tip: you can add multiple regional servers for redundancy.

sudo timedatectl set-timezone UTC
echo "server europe-central.smoothtime.io iburst" | sudo tee -a /etc/ntp.conf
sudo systemctl restart ntp   # or ntpd, depending on your distro

sudo timedatectl set-timezone UTC
# /etc/systemd/timesyncd.conf
[Time]
NTP=europe-central.smoothtime.io

sudo systemctl restart systemd-timesyncd

Open Settings › Time & language › Date & time.
Turn off Set time zone automatically.
Set the time zone to (UTC) Coordinated Universal Time.
Set the time server, for example from an administrator terminal:

w32tm /config /manualpeerlist:"europe-central.smoothtime.io" /syncfromflags:manual /update
w32tm /resync

Why it matters

Nature doesn't jump. Your clocks shouldn't either.

Chronobiology researchers criticise the abrupt 60-minute switch twice a year, which they link to social jetlag. smoothtime can't change your body's rhythm, but it does remove the jump on your own devices: their clocks drift gently instead.

Gentle adjustments

The servers shift the time gradually throughout the year, like a clock running very slightly faster or slower.

No sudden jumps

No hour skipped or repeated, and no duplicated log timestamps. Between transitions your clock can be up to an hour from official time.

Works with any NTP client

Any standard device that syncs time over NTP. No special software needed.

Who it's for

Right for some clocks, not for all.

With smoothtime, a device's "UTC" is really smooth local time, up to an hour away from real UTC. That's fine for clocks people read, and wrong for systems that compare time with the rest of the world.

Great for

Wall clocks and displays
Homelab and smart home
IoT devices
Personal machines where you want gradual local time

Not for

Authenticator / TOTP two-factor codes
Servers whose logs must line up with other systems
Kerberos and Active Directory
Certificate-sensitive, trading or finance systems

FAQ

Questions

Why do I have to set my system to UTC?

smoothtime sends your region's local time, including the smooth DST drift, instead of pure UTC. If your system also applies a local time zone, the offset is counted twice.

Does my clock match official time?

Exactly on each DST transition date. In between, smoothtime is up to one hour away from official time, changing by a fraction of a second per day. The chart above shows the difference for your region.

Which regions are supported?

11 regions: Europe West, Central and East; US Eastern, Central, Mountain and Pacific; Australia Sydney; New Zealand; Chile; and Argentina, which has no DST and uses a constant offset.

Which devices work?

Anything that can use a custom NTP server: Linux (chrony, ntpd, systemd-timesyncd), macOS, Windows, and many routers and IoT devices.

Can I use it on servers?

Only where time doesn't have to match other systems. A server synced to smoothtime treats smooth local time as UTC, up to an hour off real UTC, which breaks TOTP codes, Kerberos and Active Directory, certificate checks, and log correlation. Keep production servers on a regular NTP source.

Is it free and open source?

Yes. smoothtime is MIT-licensed and the source is on GitHub. You can also run your own server with Docker.