Fastly's Varnish-based architecture is the clearest technical differentiator in this category. Engineers can write exact cache logic in VCL, set precise cache keys, and rely on sub-second global purge to invalidate content without waiting for eventual consistency. For teams shipping fast-changing content -- APIs, e-commerce product pages, news -- this is decisive.
Fastly's CDN is purpose-built for engineering teams who need deterministic, instantly-purgeable caching at the edge.
Fastly's CDN is purpose-built for engineering teams who need deterministic, instantly-purgeable caching. Its Varnish-based architecture lets engineers write precise cache logic in VCL or use Compute@Edge. Cloudflare's CDN is more managed and opaque -- it works well but gives engineers less visibility and control over exactly what is and is not cached. Fastly wins for teams where CDN behaviour must be predictable and debuggable.
Cloudflare's CDN is operationally excellent for teams who do not need VCL-level control. Its 300+ PoP network, automatic cache behaviour, and integrated security make it a strong default choice. The trade-off is accepting Cloudflare's abstraction layer rather than controlling cache logic directly.
Route-specific evidence
Fastly's global cache purge completes in under 150ms in most regions. Content changes propagate to edge nodes immediately rather than waiting for TTL expiry or eventual-consistency propagation. For APIs and publishers, this removes a fundamental CDN reliability constraint.
Varnish Configuration Language gives engineers direct programmatic control over cache key construction, request routing, and response manipulation at the edge. Cloudflare's rules-based approach cannot fully replicate the precision of writing cache logic as code.
Fastly's edge behaviour is deterministic and inspectable. Engineers can trace exactly why a cache miss occurred, what VCL branch was followed, and what the cache key contained. Cloudflare's managed CDN is harder to reason about at this level of detail.
Checks before publishing
Fastly
Confirm CDN architecture, purge SLA, VCL documentation, Compute@Edge language support, pricing model, and WAF capabilities at fastly.com and developer.fastly.com.
Cloudflare
Confirm CDN network PoP count, Workers Wasm support, WAF features, DDoS protection scope, pricing tiers, and Zero Trust integration at cloudflare.com and developers.cloudflare.com.
Buyer fit
Use Fastly when real-time cache invalidation, VCL control, Wasm edge compute, or usage-based billing are the primary decision drivers for the engineering team.
Exception
Use Cloudflare when network scale, free plan access, integrated security breadth, or JavaScript-first Workers ecosystem outweigh Fastly's precise CDN control advantages.