AR Fast SNTP

Time synchronization should be simple.

Install the app, enter your SNTP server IP address, and let it synchronize your computer clock.

Download for Windows · Linux beta · Website · Quick start

AR Fast SNTP is a free, open-source time synchronization app for Windows engineering PCs, industrial HMIs, workstations, and anyone learning how SNTP works. A Linux desktop beta is also available.

No editing ntp.conf. No repeated service restarts. Just your server IP address.

See the app

_{Actual Windows Studio screenshot from this repository.}

Add a time server	Check synchronization status

See how to remove a server · View all original screenshots

Get started in three steps

1. Install: Download the Windows x64 installer and run setup.
2. Enter your server IP: Use the IPv4 address of your GPS-based NTP server or another trusted NTP/SNTP server.
3. Done: Open AR Fast SNTP and see the selected server, synchronization status, offset, and response time.

The synchronization service keeps running even when the app window is closed. You can add, enable, disable, or remove servers directly in Studio.

New to SNTP? The beginner's quick-start guide explains what server IP to enter, how to check the result, and a few easy troubleshooting tips.

Prefer a command line?

On Windows, this optional PowerShell helper downloads the official installer and checks its SHA-256 before starting setup:

Invoke-WebRequest https://raw.githubusercontent.com/masarray/arfast-sntp/main/tools/install-windows.ps1 -OutFile install-arfast.ps1
powershell -NoProfile -ExecutionPolicy Bypass -File .\install-arfast.ps1

Linux desktop beta

Download AR Fast SNTP for Linux x64. It includes a desktop UI and a background SNTP service. Extract the Linux package and follow the Linux setup guide.

What can you do with AR Fast SNTP?

Feature	What it means for you
Simple server setup	Enter an IPv4 SNTP server address instead of editing NTP configuration files
Automatic synchronization	Let the background service handle time updates
Network recovery	The Windows service reconnects and verifies sources after network changes
Clear status	See the selected server, offset, response delay (RTT), and events
Multiple time servers	Add and manage up to 16 IPv4 servers in Windows Studio
Free and open source	Use it, learn from it, and contribute on GitHub

Built from real engineering experience

I originally built AR Fast SNTP after spending too much time troubleshooting slow and inconsistent Windows time synchronization on industrial HMI computers.

In tests with four Windows HMI computers (two servers and two workstations), clock correction was observed in around one second. After reconnecting the LAN, synchronization recovered in approximately six seconds. These are results from those tests, rather than a promised time for every network.

The goal is still the same: let the application handle the complexity, not the engineer.

Help and development

• Quick start & common questions · Support
• Windows stable release · Linux beta
• Windows SNTP architecture · Linux service & setup
• Release history · Contributing · Security

Built with C#/.NET 8 and Avalonia. Use AR Fast SNTP on a computer where you are allowed to adjust the clock. Download the installer from the official GitHub Releases page; a checksum is provided for verification.

Licensed under GPL-2.0-or-later. Third-party notices are in NOTICE.