Understanding CDNs (Cloudflare, Bunny.net, Fastly, Akamai…): why and how do they work?

What is a CDN (Content Delivery Network) and why has it become essential for a website's performance and SEO? From must-have players to ultra-fast alternatives and solutions built for the web giants, let's take a complete look.

1. How does a CDN work?

To understand the point of a CDN, start with how the internet normally works: when a user types your website's address, their browser sends a request directly to your hosting server. If that server is in France and your visitor connects from another continent, the time it takes for data to travel (latency) increases, which slows down display.

A CDN solves this problem with a network of servers, called points of presence (PoPs), strategically spread around the globe:

• Caching: the CDN stores copies of your static files (images, CSS stylesheets, JavaScript scripts, even HTML pages) across all its servers.
• Geographic proximity: when a user visits your website, the CDN server closest to them responds. The physical distance is minimal and loading times drop sharply.

2. Why use a CDN? The benefits

• Greater speed and better Core Web Vitals: by reducing latency and response time, your performance scores – especially LCP as measured by Google – improve. This directly benefits your SEO (see our article on PageSpeed and SEO).
• Protection and security (anti-DDoS, WAF): most CDNs act as a shield in front of your server. They filter malicious traffic, block distributed denial-of-service (DDoS) attacks and hinder hacking attempts.
• Bandwidth savings: the CDN absorbs most of the delivery of static files, so your hosting is under much less strain.
• High availability: if your server suffers a temporary outage, some CDNs can serve cached versions of your pages to avoid a “site unavailable” error.

3. An overview of CDN providers

The market offers a wide variety of providers, each with its strengths, pricing and technical specifics.

Cloudflare: the unavoidable (and accessible) giant

Cloudflare is probably the best-known CDN in the world. It offers a very complete ecosystem, from content acceleration to advanced web application firewalls.

• Key strength: a generous, high-performing free plan that suits most showcase websites and blogs. Its security options and caching rules are very powerful.
• Who is it for? From small businesses to large groups, anyone can use it, although advanced options require some technical configuration.

Bunny.net: the fast, affordable European alternative

Bunny.net specialises in top-level performance with a philosophy built on simplicity and very low volume pricing.

• Key strength: delivery speeds among the best on the market, a clean interface and pay-as-you-go billing: you only pay for the gigabytes actually used.
• Who is it for? E-commerce stores, image- and video-rich websites, and agencies looking for excellent value without the complexity of the big players.

Fastly: the choice of developers and real time

Fastly is a premium CDN favoured by tech companies, media and development teams looking for very fine control.

• Key strength: purging and updating the cache worldwide in a fraction of a second, with edge computing features to run logic directly on the network.
• Who is it for? Dynamic applications, high-traffic websites and advanced technical teams.

Akamai: the pioneer and enterprise giant

Akamai is historically one of the first and one of the largest content delivery networks in the world.

• Key strength: a massive global presence and top-level defences against cyberattacks and malicious bots.
• Who is it for? Large companies, international groups and video streaming platforms that need rock-solid robustness.

CDNs from the cloud giants

If your website or application already runs on a major cloud infrastructure, using its native CDN is a logical choice:

• Amazon CloudFront: fully integrated with the AWS ecosystem, it offers great flexibility.
• Google Cloud CDN: it relies on Google's global network.
• Microsoft Azure Front Door (successor to Azure CDN): ideal for businesses already using Microsoft solutions.

CDN comparison table

Conclusion

Setting up a CDN is no longer a luxury reserved for multinationals: it is an essential technical lever to speed up your website, reassure your visitors and look after your SEO. On WordPress, it works best combined with a good caching plugin (see our article on optimising a WordPress website).

Would you like to choose the right CDN and integrate it properly into your website? Contact us to discuss it and boost your website's performance.

Frequently asked questions

Franck GuigoutFounder of GUIGOUT SAS, a web agency in Bourg-en-Bresse, France. Over twenty years of building WordPress and WooCommerce websites and of search engine optimisation for businesses in France and abroad.