How CDN Caching Works and Why You Need It in 2025

Published on July 4, 2025

Every website is a global website and even one extra millisecond of delay can be the difference between a conversion. Thus, CDNs (Content Delivery Networks) and caching are two of the best technologies available to date to speed up your website.

Learn how they work together and why you need them if you're a serious online business in 2025.

1. What Is a CDN?

A Content Delivery Network is a distributed network of proxy servers located all over the world to supplement the workings of an origin (where your site is hosted) server. Rather than loading information from your web host, a CDN stores your files on edge nodes—servers located closer to your customers and visitors.

Some popular CDNs are:

• Cloudflare
• Bunny.net
• Akamai
• Fastly
• Amazon CloudFront

When an interested visitor accesses your site, their browser requests a file (HTML, style sheets, JavaScript, photos) and the CDN:

1. Checks if it's in its cache
2. If it is → serves it right away
3. If it's not → fetches it from your origin server and then caches it for the next person

2. How CDN Caching Works

Caching is defined as storing frequently-used information in a location that is more accessible to a user. CDN caching occurs based on:

• HTTP headers (Cache-Control, Expires)
• Query string rules
• File type (static vs dynamic)
• Page rules or purge triggers

Files can be cached for:

• A few minutes (e.g., dynamic APIs)
• Hours (e.g., blog posts)
• Days (e.g., images, CSS)

With increasingly complex configurations available through CDNs in 2025, we can now cache through newer options like:

• Smart cache invalidation
• Edge workers to use custom logic
• Dynamic content caching through originless APIs

3. Performance Benefits

In 2025 caching isn't just about speed anymore. A proper caching solution increases many metrics that lead directly to revenue generation and customer satisfaction:

• ⏱️ Load Times: Initial paint load time can be cut down by 50–90%.
• 🧠 Lower Origin Server Load: No need to scale infrastructure anymore with ability to manage high traffic.
• 🌍 Serve Where Users Are: CDN has nodes across the globe, so users can be served from wherever they are (e.g., Asia, EU, South America).
• 🔒 Better Security: With DDoS mitigation, bot filtering, rate limiting occurs at the edge.

4. Cache-Control Best Practices

To ensure your caching solution is successful and functional:

• Set Cache-Control: public, max-age=31536000 on your static files.
• Use stale-while-revalidate to offer faster load while simultaneously checking in the background for updates.
• Avoid cache busting via random query strings—use hashed filenames instead.
• Only purge when necessary. Automate purging via API integrations.

5. How to Get Started

✅ Utilize our Free CDN Analyzer:
Analyze what's currently going on with your cache strategy and receive speed recommendations tailored to you.

🌐 Less than 10 minutes to onboard with these options:

• Cloudflare free tier
• GitHub Pages + BunnyCDN for JAMstack sites
• WordPress with WP Rocket or FlyingPress

Conclusion

CDN caching is no longer optional in 2025. It's essential. Whether you’re scaling a global SaaS platform or running an optimized personal blog, edge caching and global delivery offer massive advantages in load time, server efficiency, and data security. Make caching a first-class citizen in your performance stack—your users (and bottom line) will thank you.