In traditional SEO practices, changes like meta tag updates, redirects or content adjustments are typically made on the origin server, which then distributes these updates to users via content delivery networks (CDNs).
This process can be slow and cumbersome, particularly for large websites or those with global audiences. With edge SEO, these changes are implemented at the network’s edge, closer to the user, allowing for real-time updates and reducing latency.
This practice also helps overcome challenges posed by complex server infrastructures, where making server-side changes can be time consuming or technically difficult.
Before the phrase “edge SEO” was officially introduced, the concept was already taking shape in the minds of forward-thinking SEOs and developers. I’m fortunate to have been credited with coining the phrase at the TechSEO Boost conference in 2018.
What is edge SEO?
Edge SEO involves implementing technical SEO recommendations (and code) through a serverless application, such as Cloudflare Workers, deployed on a CDN.
This approach allows website changes without altering the site’s underlying code base. It works by modifying the request and response interactions between the client — whether it’s a user or a search engine like Googlebot.
As shown in the example below, the left side displays the direct server response, while the right side shows the response as rendered by a user or search engine:
The difference is the addition of hreflang, which is injected into the head by a Cloudflare Worker.
How does edge SEO impact page load speed?
When it comes to page load speed, edge SEO can introduce some latency, but the impact is minimal. Based on tests conducted on real-world websites, the average added latency is around 10 milliseconds (ms).
During our testing and in rare cases, the latency might increase to as much as 50 ms.
This typically occurs due to factors such as the platform being used or the size of the packets returned by the server.
Websites that serve large packets, uncompressed media or oversized images, especially those with slow performance in general, may experience a slight amplification of this latency.
Nonetheless, the overall impact on page speed remains minor in most scenarios.
If you’re using Cloudflare as your CDN, you may already use minification, Brotli and other speed optimization tools.
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What change can be implemented with edge SEO?
Edge SEO offers a wide range of modifications, providing plenty of opportunities to optimize a website or quickly fix issues, even when the traditional development queue is slow.
Redirect implementation
You can set up various types of redirects, such as 301 (permanent) and 302 (temporary) redirects, to ensure proper SEO handling of page changes. This can be vital for platforms with redirect limits, such as Salesforce Commerce Cloud or SAP Hybris.
Changes can be made to the HTTP header responses, like adding or altering the X-Robots-Tag, which controls how search engines crawl and index specific pages.
Robots.txt modifications
Edge SEO allows you to modify or create a robots.txt file, even on platforms with restrictions, such as Shopify, to better control which parts of your site are crawled by search engines.
JavaScript pre-rendering
You can implement pre-rendering solutions to deliver fully rendered pages to search engines, which can help with SEO on JavaScript-heavy websites.
Collecting server logs
Edge SEO enables the collection of server log files, including from platforms that don’t traditionally allow you to access log files, to analyze and optimize your strategy based on real user and bot interactions.
Content injection and overwriting
New content can be injected into pages and existing content (i.e., meta titles, descriptions and body text) can be overwritten without modifying the core code.
Schema markup implementation
You can add structured data through schema markup to improve how search engines understand and display your content in rich search results.
Hreflang tag management
Edge SEO enables the implementation and management of hreflang tags, even when content is hosted on multiple platforms or ccTLDs. This ensures proper language and regional targeting across a website.
Which CDNs offer this functionality?
Several CDNs offer this kind of functionality as part of free, freemium and premium plans.
Not all providers offer the same range of functionality, but from our research, the core functionalities address the major (or most common) technical SEO needs.
- Cloudflare Workers.
- AWS Cloudfront with Lambda@Edge.
- Fastly Compute@Edge.
- Akamai EdgeWorkers.
- Azure with Azure Functions.
- BunnyCDN with Edge Scripts.
Netlify offers serverless functions that can run in response to HTTP requests, which can be used with their CDN capabilities. Likewise, Vercel also offers a range of serverless functions for dynamic content.
Using edge SEO techniques responsibly
Edge SEO provides a valuable way to implement changes, whether for a short-term fix to ease the development team’s burden or for a longer-term feature that improves user experience.
It’s essential to avoid working in isolation. Just because this technique allows you to bypass making changes to the codebase directly, it doesn’t mean that it should bypass the development/engineering team.
Ensure that your development team is involved and informed about the changes being made through the CDN, adhering to their deployment and testing guidelines.
This communication is crucial, as standard development practices could inadvertently introduce bugs or create misleading issues during testing phases, potentially impacting the site’s overall functionality.
Why edge SEO?
For some, edge SEO may appear to be just another trend to explore or a luxury tool lacking real value.
However, it has the potential to significantly enhance the SEO capabilities of many SEOs and in-house digital teams.
These teams often encounter real-world challenges from custom platforms, legacy technology stacks or specific configurations that complicate implementation.
Addressing technical challenges with edge SEO
Edge SEO represents a transformative approach to website optimization, enabling real-time updates and modifications without altering the underlying code base.
By leveraging CDNs and serverless applications, you can address complex SEO challenges more efficiently, ultimately enhancing user experience and site performance.
Edge SEO lets businesses stay agile and responsive to meet user and search engine needs effectively.
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