this post was submitted on 19 Apr 2026
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Programming

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[–] tias@discuss.tchncs.de 15 points 1 day ago (1 children)

If your device’s clock is set to the wrong time, it should tell you how far off the clock is set.

Why are we assuming that your HTTP-based method running in JS in a browser, using servers that are already distributed and time-synched with tech stacks that you have no insight into, is the "right time" and the directly NTP-synchronized clock of my machine is the "wrong time"?

[–] robalex@programming.dev 3 points 18 hours ago

Hey, author here. You're asking a couple questions, which I'll try to unpack.

You're right to be suspicious that Cloudflare CDN servers have the right time. I tried to call out that concern in the post. Cloudflare operates time services, but their CDN is not a time service and wouldn't be operated under the same controls. How accurate those servers are is an open question.

When writing the post I observed NTP client logs, a GPS-based clock, and the CDN-based clock report time that agreed within their stated error bounds. I've also seen NTP-synchronized and mobile network synchronized system clocks that fell outside the estimates of those other clocks. So it's an "odd one out" situation.

But I think you are asking the right questions!