On Google’s Signed Exchange (SXG) Program

Speed and load times are very important back-end factors within the SEO world, and major search engines like Google are regularly rolling out updates to improve processes here. One major such update that's recently been rolled out to all site types is known as Signed Exchange, or SXG -- what is this program, and how might it benefit your site?

At SEO Werkz, we're happy to help with a variety of SEO solutions, including in areas like on-site optimization and web design that help clients maximize the quality and responsiveness of their customer-facing websites. Let's go over everything you need to know about Signed Exchanges and how they work, the benefits they offer to sites across the web, and how to get started with them.

Signed Exchange Basics

Originally introduced by Google primarily for AMP sites several years ago, Signed Exchanges have now become available for all sites across the web. Signed Exchange refers to an open standard delivery mechanism that allows users to access content directly from an origin server.

How does this work? A Signed Exchange doesn't actually store a copy of the requested resource on their servers, but when a user searches, Google pre-loads some of your content from the SXG. This improves speed and reduces load times by not transferring data over HTTP -- which is the most common way that web pages are currently served, but also one of the slowest.

While SXG is intended for high-quality sites that want to offer engaging search experiences to their users, there is also a lot that you can do as a developer to help improve the experience. If you think your site might benefit from implementing this new spec, we'd love to help!

Technical Side of Signed Exchanges

Here are the basic steps that will be followed to generate a Signed Exchange for your site:

• In advance, before content is being published on a given page, you will negotiate with Google to create a Signed Exchange (this is done through request headers).
• The original content you'll be using, including its response headers, will be obtained.
• A Digest header will be added to the content, allowing progressive data detection and other basic back-end themes.
• Any headers that don't make sense within Signed Exchanges, plus any that are specifically security-sensitive (such as Authentication-Info, for instance), will be stripped out before the Signed Exchange is created.
• All the remaining headers, including the Digest header, are then combined with any other metadata like URL certificates or expiration times and chained together, forming a single stream that's used to calculate the final signature.
• The original content plus its headers, signature and a fallback URL, are packed into a binary that delivers the Signed Exchange.

From here, the exchange will be cached and sent to the crawler, where it's eligible to show up in searches. When any web user clicks on a link to your content, they receive the Signed Exchange in a response from Google.

Benefits of Signed Exchange

Now that you have a basic understanding of how SXGs work, let's talk about how publishers might benefit from implementing them within their websites. These benefits include:

• Greater consistency: SXGs show up in a more consistent way across all types of devices and browsers.
• Faster response times: Users view pages with SXGs more quickly than pages without them.
• Improved performance: As mentioned above, content is transferred using progressive data detection and compressed URLs, which makes for a faster user experience; the webpages involved in Signed Exchanges load much faster and use exponentially less bandwidth than traditional webpages.
• Improved indexing: Performance is optimized for crawlers, meaning they have to do less work indexing your page and can instead focus on other tasks.
• Portable content: SXGs also makes content portable, allowing it to be delivered by third parties and eventually leading to fully offline experiences that still benefit your branding themes. There could come a day where virtually every site on the web supports the SXG standard, allowing all linked articles to be pre-loaded and improving site load times in massive ways.

Not a Simple Process

The process of generating and maintaining Signed Exchanges is somewhat complex and reveals the benefits of working with a high-quality SEO company. Here are some of the considerations you have to keep in mind:

• Certificates have to be delivered in specific CBOR formats, such as binary JSON or others.
• Because validity of certificates is so important within this realm, OCSP stapling is required to maintain it.
• Signed Exchange certificates need renewal on a much more frequent basis than other formats, and may require automation for this process.
• Because Signed Exchanges aren't cheap to create, caching those that have been created is very important. We'll manage this entire area for you.

Staying Updated

Like many other parts of the SEO world, especially with regard to Google's changing emphases, it's important to keep track of updates within the SXG realm. SEO marketers and in-depth business owners should consider signing up for the webpackaging-announce mailing list from Google themselves, which offers information on things like changes to the Google SXG cache, new capabilities being added (or older capabilities being depreciated), and even larger changes to SXG tools Web Packager, the NGINX SXG module, and several other areas. And as always, if you're working with us at SEO Werkz, we'll keep track of these updates on your behalf.

For more on Signed Exchange, or to learn about any of our other SEO services, speak to the staff at SEO Werkz today.