CDN Strategy for Web Apps: Cloudflare vs Fastly vs CloudFront

Content Delivery Networks started as distributed caches for static files. Today, they are programmable edge computing platforms. The right CDN improves performance (serve content from the nearest edge location), security (DDoS protection, WAF, bot mitigation), reliability (failover if your origin server goes down), and cost (reduce origin bandwidth and compute).

For a web application, your CDN handles: static assets (images, CSS, JS, fonts), API responses (cacheable endpoints), full-page caching (for marketing pages and blog posts), SSL termination, image optimization and resizing, and edge functions (running code at the edge for personalization, A/B testing, and geolocation).

If you are not using a CDN, your users in Tokyo are fetching every asset from your server in Virginia. That adds 150 to 300ms of latency to every request. A CDN eliminates that by serving from a server 10ms away.

Cloudflare is the largest CDN by number of websites (over 20% of the internet). It is the default recommendation for most web applications because of its generous free tier, developer-friendly platform, and comprehensive feature set.

Pricing

• Free: Unlimited bandwidth, DDoS protection, SSL, basic WAF, and 100K Workers requests/day. Yes, seriously free. This covers most startup needs.
• Pro ($20/month): Image optimization (Polish), mobile optimization, enhanced WAF rules, and better analytics.
• Business ($200/month): Custom WAF rules, 100% SLA, advanced DDoS, and priority support.
• Enterprise (custom pricing): Dedicated support, custom configurations, advanced security, and guaranteed performance.

Standout Features

Cloudflare Workers: Run JavaScript at the edge with V8 isolates. Zero cold starts, 0ms startup time, 200+ edge locations. Use Workers for A/B testing, geolocation-based redirects, API rate limiting, and request transformation. Workers are the most developer-friendly edge computing platform available.

R2 Storage: S3-compatible object storage with zero egress fees. Store images, videos, and files on Cloudflare's network without paying bandwidth charges. Replaces S3 for many use cases and saves significant money at scale.

Cloudflare Images: Image hosting, optimization, and transformation via URL parameters. Upload once, serve optimized variants with width, quality, and format parameters in the URL. Eliminates the need for a separate image processing pipeline.

Limitations

Cache purging is not instant (can take up to 30 seconds globally). Fine-grained caching control requires Workers or Page Rules, which adds complexity. Enterprise features are expensive compared to alternatives.

Fastly is the CDN for engineering-heavy teams that want granular control over caching behavior. Stripe, GitHub, The New York Times, and Shopify use Fastly.

Pricing

Pay-as-you-go starting at $0.12 per GB (US) with no minimum commitment. More expensive per-GB than Cloudflare's free tier but cheaper than CloudFront for most workloads. Pricing varies by region ($0.12 to $0.28 per GB).

Standout Features

Instant purge: Cache purging completes globally in under 150ms. If your application requires content to update immediately after changes (news sites, ecommerce inventory, dynamic pricing), Fastly's purge speed is unmatched. Cloudflare takes up to 30 seconds; Fastly takes milliseconds.

VCL (Varnish Configuration Language): Fastly is built on Varnish and exposes VCL for advanced caching logic. You can write complex cache rules: vary caching by custom headers, implement stale-while-revalidate, and create sophisticated routing logic. Powerful but requires learning VCL.

Compute@Edge: Fastly's serverless platform using WebAssembly. Supports Rust, Go, JavaScript, and other languages compiled to WASM. Cold starts under 35 microseconds. For compute-intensive edge workloads, Compute@Edge outperforms Workers.

Limitations

No free tier. The developer experience is rougher than Cloudflare (VCL has a learning curve). Smaller edge network than Cloudflare (80+ PoPs vs 200+). Better suited for teams with dedicated infrastructure engineers.

Amazon CloudFront is AWS's CDN. It integrates deeply with other AWS services, making it the natural choice if your infrastructure is already on AWS.

Pricing

$0.085 per GB (first 10TB, US/Europe). Gets cheaper at scale. Free tier includes 1TB of data transfer and 10M HTTP requests per month for the first year. After the free tier, CloudFront is typically more expensive per-GB than Cloudflare Pro but comparable to Fastly.

Standout Features

AWS integration: Native integration with S3 (origin access control), Lambda@Edge (edge computing), ALB (load balancing), WAF (web application firewall), and Shield (DDoS protection). If you are already using these services, CloudFront fits seamlessly.

Lambda@Edge: Run Node.js or Python functions at CloudFront edge locations. Similar to Cloudflare Workers but with access to AWS APIs and services. Cold starts are 1 to 5ms (slower than Workers' 0ms). Supports four trigger points: viewer request, origin request, origin response, and viewer response.

Origin Shield: An additional caching layer between edge locations and your origin server. Reduces origin load by collapsing multiple edge requests into a single origin request. Saves money on origin compute costs.

Limitations

Configuration is complex (CloudFront distributions have dozens of settings). Cache invalidation takes 1 to 2 minutes (slower than both Cloudflare and Fastly). The web console UI is clunky compared to Cloudflare's dashboard. No free DDoS protection (AWS Shield Standard is free but limited; Shield Advanced costs $3,000/month).

A CDN is only as good as your cache configuration. Poor cache settings mean every request hits your origin server, defeating the purpose entirely.

What to Cache

• Static assets (CSS, JS, images, fonts): Cache aggressively with long TTLs (1 year). Use content hashing in filenames (style.a3f2b1.css) so new versions get new URLs and old cache entries expire naturally.
• Marketing pages and blog posts: Cache for 5 to 60 minutes. Use stale-while-revalidate to serve cached content while fetching fresh content in the background.
• API responses: Cache GET requests for read-heavy endpoints (product listings, public profiles). Set short TTLs (30 seconds to 5 minutes) with proper Vary headers for user-specific content.

What NOT to Cache

• Authenticated API responses (user-specific data)
• POST/PUT/DELETE requests
• Real-time data (stock prices, live chat)
• Checkout and payment pages

Cache Headers

Set proper Cache-Control headers from your origin server. The CDN respects these headers unless you override them. For static assets: Cache-Control: public, max-age=31536000, immutable. For dynamic content: Cache-Control: public, s-maxage=300, stale-while-revalidate=60. The s-maxage directive targets shared caches (CDNs) while max-age targets browser caches.

CDNs are your first line of defense against DDoS attacks, bots, and web application attacks.

DDoS Protection

Cloudflare: Free unlimited DDoS protection on all plans. Mitigates Layer 3/4 and Layer 7 attacks automatically. The free tier includes DDoS protection that most other providers charge thousands for. This alone makes Cloudflare worth using.

Fastly: DDoS mitigation included but with less public detail on capabilities. Network-level protection on all plans. Application-level protection requires additional configuration.

CloudFront: AWS Shield Standard (free) provides basic DDoS protection. Shield Advanced ($3,000/month) provides comprehensive protection with a dedicated response team and cost protection (AWS credits you for scaling costs during an attack).

Web Application Firewall (WAF)

Cloudflare: Free tier includes basic WAF. Pro adds managed rulesets (OWASP Core Rule Set). Business and Enterprise allow custom rules.

Fastly: Next-Gen WAF (acquired from Signal Sciences) is a separate product. Excellent detection accuracy. Starts at custom pricing.

CloudFront: AWS WAF is a separate service ($5/month per web ACL plus $1 per rule plus $0.60 per million requests). Powerful but requires manual rule configuration.

For most startups and growth-stage companies, here is our recommendation:

Default choice: Cloudflare. The free tier is absurdly generous. DDoS protection, SSL, CDN, and basic WAF at zero cost. Workers provide edge computing when you need it. R2 eliminates egress costs for file storage. Start with Cloudflare and only consider alternatives when you have specific requirements it does not meet.

Choose Fastly if: You need instant cache purging (sub-second globally), your engineering team wants granular control over caching logic via VCL, or you run a high-traffic ecommerce or media site where cache accuracy directly affects revenue.

Choose CloudFront if: Your infrastructure is deeply integrated with AWS (S3 origins, Lambda@Edge, WAF rules), you need the AWS compliance certifications (FedRAMP, HIPAA eligibility), or your team already knows AWS and does not want to manage another vendor.

Implementation Costs

• Basic CDN setup (1 to 2 days, $1K to $3K): Configure CDN, set cache rules, point DNS, verify SSL. Any experienced DevOps engineer can do this in a day.
• Advanced CDN configuration (3 to 5 days, $3K to $8K): Custom cache rules, edge functions, image optimization, WAF configuration, and monitoring setup.
• Full edge architecture (2 to 4 weeks, $10K to $25K): Edge computing for personalization, multi-CDN failover, advanced security rules, and performance monitoring.

We help companies choose and implement the right CDN strategy for their performance and security requirements. Book a free strategy call to discuss your infrastructure needs.