tl;dr: If you’re using How’s My SSL’s API for checking the TLS version of your users’ browsers, please use tlsversion.com’s API instead.

Site operators have long been using howsmyssl.com on their websites to tell what version of TLS their web users are using. In fact, most of the 5.6 million requests per day (65 requests/sec) are exactly those kinds of requests and use no other data from the JSON howsmyssl.com response.

There’s no web-standard API to get the TLS version of a user’s browser from the browser, so How’s My SSL has shown up in Stack Overflow answers and, now, AI summaries as the answer to that problem. But How’s My SSL does a fair amount of work that the folks just needing a TLS version aren’t using. That work – those unused feature and vulnerability detections – adds latency to the end users' requests, and increase resource use in How’s My SSL.

So, if your site just needs to know the TLS version of the browser connecting to it, consider using tlsversion.com, and specifically its JSON API.

Tlsversion.com is a faster, more reliable way to get that TLS version information. (And, handily, even supports HTTP/3).

Here’s a quick example of how to use tlsversion.com:

const res = await fetch("https://tlsversion.com/v1/version.json");
const data = await res.json();
console.log(data.version); // "TLS 1.3"