CloudFront and Lambda@Edge: Delivering Dynamic Content at the Edge

The Edge Computing Paradigm

Traditionally, your applications run in a single region. CloudFront caches static content at the edge — but with Lambda@Edge, you can also move logic to the edge.

Use Cases for Lambda@Edge

• A/B Testing: Route different user groups to different origins — without any changes to the application.
• Geo-Routing: Redirect users to the nearest region based on their location.
• Auth at the Edge: JWT validation directly at the edge — unauthorized requests never reach your origin.
• Image Optimization: Resize images on the fly and convert to WebP/AVIF — based on the client.

CloudFront Functions vs. Lambda@Edge

• CloudFront Functions: Lightweight (JavaScript), sub-millisecond execution, ideal for header manipulation and URL rewrites.
• Lambda@Edge: Full-fledged Lambda functions (Node.js, Python), up to 30 seconds execution time, access to external APIs.

Performance Gains

In an international e-commerce project, we reduced the Time to First Byte (TTFB) through edge computing from an average of 450 ms to 35 ms — a difference your customers will notice.