This pairing is the classic velocity-versus-gravity decision, and under the hood the architectures could hardly differ more. Fastly runs few, large, memory-rich POPs with software it wrote from the metal up; CloudFront runs Amazon’s sprawling edge tied intimately into AWS.
Configuration and compute
Fastly’s defining property is instant, versioned configuration: VCL or Compute deploys propagate globally in seconds, with real-time logs to match. CloudFront configuration historically propagates in minutes, with Functions and Lambda@Edge covering lightweight and heavier logic respectively at different price and latency points. Teams that treat delivery as code feel this difference every single day; teams that configure once feel it never.
Caching architecture
Fastly’s shallow hierarchy and huge per-POP memory produce excellent hit ratios per site, with instant purge, purge by surrogate key, as a first-class primitive that media teams build workflows on. CloudFront leans on its regional edge cache tier and Origin Shield to protect origins, with invalidations that are slower and billed. For catalogs that change constantly, purge semantics alone can decide this matchup.
A subtlety worth engineering attention: the two platforms’ observability models differ in kind, not degree. Fastly streams per-request logs in real time to your endpoint of choice, which turns the CDN into a debuggable component of your stack. CloudFront’s logging has improved but remains batch-flavored, with real-time logs an add-on carrying its own pricing and setup. During incident response, the gap between seconds and minutes of log latency is the gap between diagnosis and archaeology, and it belongs in the comparison spreadsheet next to the per-GB rate.
The AWS gravity well
CloudFront’s unfair advantage is the bill: free origin fetch from AWS services, IAM-integrated security, one invoice, and the political ease of the default. The honest counterweight is measured: dynamic-path latency, real request pricing at your object sizes, and the engineering hours your team spends fighting slower feedback loops. Free-shaped is not the same as cheap.
In practice
Route the decision through three numbers: your requests-per-GB ratio priced on both models, your team’s realistic edge-logic velocity, and origin egress under each architecture. AWS-native teams shipping stable workloads keep CloudFront and negotiate committed-use discounts; product teams programming the edge buy Fastly and bank the velocity. Mixed estates increasingly run both, one per job.
We quote Fastly on your request profile and model CloudFront’s true blended cost, egress included. The numbers usually end the debate.