Web Development

About Automatic Signed Exchanges (SXGs) and LCP Load Times

Cloudflare is taking performance & website load times very seriously when it comes to assisting users who leverage their services. Quite recently, it launched a beta on early hints 103 HTTP code.

Almost hand in hand, it seems, they also unveiled the “Automatic Signed Exchanges” beta in partnership with Google — with the primary purpose of improving Largest Contentful Paint (LCP) times, one of the Core Web Vitals.

To unravel how this works automatically from a layman’s perspective, we first need to get a simple understanding of what Signed Exchanges, or (SXGs), in technical jargon, are.

What Are Signed Exchanges (SXGs)?

An initiative from Google, a Signed Exchange allows for a fast & easy content delivery, which in turn makes the web pages load faster — because of how browser caching works.

Essentially, it makes your content portable, so when it comes to sharing, distribution, etc., basically activities such as those that allow your content to be seen publicly, the content on your site is loaded faster.

The portability aspect (so think lighter and faster) is where the entire focus is, and for all things considered, and in non-technical terms, it has a considerable potential to load your pages swiftly, and effectively, improve load times for LCP elements.

You can imagine SXGs as a cacheable copy of your website that is better for performance for the events when users click on the links to your site from third parties, such as a Google Search Results Page or news aggregators.

How Signed Exchanges Work (SXGs)

Part of the Signed Exchange process involves verifying where the content originated from. To that end, a request/response pair is served, so that an SXG copy of your site can be shown from any caching server.

You can visualize this as a lock and key mechanism where this pairing is unique to your site / URL / Web page.

In any case, for an SXG to successfully work, fundamentally, we need to have two setups in place:

  1. Setup 1 is having the ability of a website to create SXGs.
  2. Setup 2 is having the ability of a third party, again as an example, a Google search result page, to show an SXG copy of your site. What browser you use can play a role too.

To help you paint a picture, take a look at the screenshot below that is captured directly from Google’s resource.

how signed exchanges work is equivalent to setup 1 described above. is like setup 2 where it can serve an SXG copy of site A. Image source: Google Developers.

Right now, SXGs feels like it’s in the baby stages, and only a handful of third-party systems and organizations can support it comfortably. Google obviously, as they’re the ones who introduced it, and Cloudflare.

Technically speaking, creating a SXG is a convoluted process and involves knowledgeable Devs, so I am sure not many websites even know about this possibility or don’t know how to create one. As a matter of fact, Google has a page on getting started with SXGs listed under Advanced SEO, indicating that enabling SXG functionality is not a straightforward approach.

How To Kick Off Automatic Signed Exchanges (SXGs) on Cloudflare?

The beauty of being on Cloudflare is that you can turn on Automatic Signed Exchanges (SXGs) for your WordPress or another CMS-based site with just a switch of a toggle button.

Turning on Automatic Signed Exchanges on Cloudflare
As shown, with Cloudflare, permitting Automatic Signed Exchanges to work as a feature on your site is as easy as turning a toggle switch to on.

Do note, though, that to get access to this feature, you would either need to pay for a pro or higher Cloudflare subscription or pay for its Automatic Platform Optimization (APO) service.

Current Limitations of Signed Exchanges

As alluded to, Signed Exchanges isn’t widely adopted, and therefore comes with limitations. A screenshot image will be provided right after the bullet points below for a complete list, but the important ones that matter for now are:

  • Signed Exchanges are only supported on Google for Android Search. It is said that adoption on desktop browsers will be coming, but no timeline has been given.
  • As far as the search results go, Google only advocates Signed Exchanges for its top results.
  • See a full list in the image that follows.
Limitations of Signed Exchanges
Limitations of Signed Exchanges. Screenshot captured from Cloudflare, after logging into the account.

Are There Other Benefits of Signed Exchanges (SXGs)?

The scope of Signed Exchanges takes us beyond the speed optimization aspect of web experience. In addition to assisting with improving LCP load times, a few more exciting benefits are specified in the Google Developers documentation. It’s a bit technical, but you can take a look to see if it makes sense to you.

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Limited slightly in extent and widespread acceptance for now, Signed Exchanges (SXGs) hold tremendous potential on making the internet faster because of how it is created and how it works. For SEO reasons, it assists with loading your Largest Contentful Paint element quicker.

With Cloudflare, you can get a chance to see this new initiative in the works with a simple switch of a toggle button. To get there, login > then head over to “Speed” options from the top. Next, click on the “optimization” tab, and in there, you’ll see an option of Automatic Signed Exchanges (SXGs).

Expert sources & citations