Edge computing provides general-purpose compute resources at the network edge for running applications, while CDN (Content Delivery Network) specializes in caching and delivering static content. Edge computing can process data and run code; CDN primarily serves cached files.
Quick Comparison
| Aspect | Edge Computing | CDN |
|---|---|---|
| Primary purpose | Run applications and process data | Deliver cached content |
| Compute capability | Full compute (CPU, GPU, memory) | Limited (Edge Workers) |
| Programming model | Containers, Functions, VMs | Edge Workers/Lambda@Edge |
| State | Can maintain state | Stateless caching |
| Latency | 1-10 ms for compute | 1-5 ms for cache hits |
| Use cases | AI inference, real-time apps, APIs | Static assets, video, images |
| Cost model | Compute time + data transfer | Data transfer (bandwidth) |
| Data handling | Transform, filter, process | Cache and serve |
What is Edge Computing?
Edge computing places compute resources at the network perimeter—close to users and data sources. These resources can run arbitrary code, maintain state, and process data in real time.
Capabilities:
- Run containerized applications
- Execute serverless Functions
- Perform AI/ML inference
- Process streaming data
- Maintain local databases
- Transform and filter data
Example: A retail application running fraud detection at the edge. The edge node receives transaction data, runs a machine learning model, and returns a fraud score in <10ms—all without contacting a central server.
What is a CDN?
A Content Delivery Network distributes cached content from servers positioned close to users. CDNs store copies of static files (images, videos, CSS, JavaScript) and serve them from the nearest location.
Capabilities:
- Cache static content at edge locations
- Serve files from geographic proximity
- Reduce origin server load
- Accelerate content delivery
- Provide DDoS protection
- Terminate SSL/TLS
Example: A news website caches article images and CSS files on a CDN. When a user in South Africa requests the site, files are served from a Johannesburg CDN node in <5ms instead of traveling from a US origin server.
Key Differences
Compute vs Cache
Edge Computing:
- Executes code: Python, JavaScript, Go, Rust
- Processes requests dynamically
- Can modify responses per user
- Runs AI models for inference
- Handles complex business logic
CDN:
- Serves pre-computed content
- Limited compute via Edge Workers
- Primarily cache lookup and delivery
- Cannot run arbitrary applications
- Optimized for read-heavy workloads
State Management
Edge Computing:
┌─────────────────────────────────────────────┐│ Edge Node ││ ┌──────────┐ ┌──────────┐ ┌──────────┐ ││ │ Compute │ │ State │ │ Database │ ││ │ (Code) │←→│ (Memory) │←→│ (Local) │ ││ └──────────┘ └──────────┘ └──────────┘ │└─────────────────────────────────────────────┘ │ ▼ Can maintain session state, local cache, counters, queuesCDN:
┌─────────────────────────────────────────────┐│ CDN Node ││ ┌──────────┐ ┌──────────┐ ││ │ Cache │ │ Config │ ││ │ (Files) │ │ (Rules) │ ││ └──────────┘ └──────────┘ │└─────────────────────────────────────────────┘ │ ▼ Stateless. Each request independent. No memory between requests.Latency Characteristics
Edge Computing Latency:
- Simple request: 1-5 ms
- Compute-intensive: 10-100 ms
- AI inference: 5-50 ms
- Database query: 5-20 ms
CDN Latency:
- Cache hit: 1-5 ms
- Cache miss (origin fetch): 50-500 ms
- Static file serving: <5 ms
Use Case Comparison
| Use Case | Edge Computing | CDN | Better Choice |
|---|---|---|---|
| Static website hosting | Possible | Optimized | CDN |
| Image/video delivery | Possible | Optimized | CDN |
| API endpoint with logic | Optimized | Limited | Edge |
| AI inference | Optimized | No | Edge |
| Real-time personalization | Optimized | Limited | Edge |
| A/B testing | Optimized | Possible | Edge |
| SSL termination | Both | Both | Either |
| DDoS protection | Both | Both | Either |
When to Use Edge Computing
Choose edge computing when you need to:
- Run custom application logic at the edge
- Perform AI/ML inference with low latency
- Process API requests with business logic
- Transform or filter data before delivery
- Maintain session state close to users
- Handle complex routing decisions
- Execute real-time personalization
- Aggregate data from multiple sources
Examples:
- Authentication and authorization at the edge
- Real-time fraud detection
- Dynamic content transformation
- IoT data processing and filtering
- Real-time bidding in advertising
When to Use a CDN
Choose a CDN when you need to:
- Deliver static assets (images, videos, CSS, JS)
- Cache HTTP responses for repeated requests
- Reduce origin server load
- Accelerate content delivery globally
- Protect against DDoS attacks
- Terminate SSL/TLS efficiently
- Stream video to large audiences
Examples:
- Website static asset delivery
- Video streaming platforms
- Software distribution
- E-commerce product images
- News site content delivery
The Convergence: CDN + Edge Computing
Modern platforms combine CDN and edge computing capabilities:
┌────────────────────────────────────────────────────────────┐│ Edge Platform ││ ││ ┌─────────────┐ ┌─────────────┐ ┌─────────────┐ ││ │ CDN │ │ Compute │ │ API │ ││ │ Caching │ │ Functions │ │ Gateway │ ││ │ │ │ │ │ │ ││ │ Static: │ │ Dynamic: │ │ Routing: │ ││ │ Images, JS │ │ Logic, AI │ │ Rate limit │ ││ │ CSS, Video │ │ Transform │ │ Auth │ ││ └─────────────┘ └─────────────┘ └─────────────┘ ││ ││ ┌─────────────────────────────────────────────────────┐ ││ │ Shared Infrastructure │ ││ │ Global Network | Security | Observability │ ││ └─────────────────────────────────────────────────────┘ │└────────────────────────────────────────────────────────────┘Azion, Cloudflare, Fastly, and Akamai all offer integrated edge platforms that provide both CDN caching and edge compute capabilities.
Architecture Patterns
Pattern 1: CDN for Static, Edge for Dynamic
Request → Edge Platform │ ├── Static file? → CDN Cache → Response (2ms) │ └── Dynamic request? → Edge Function → Response (15ms) │ └── Need origin? → Origin ServerPattern 2: Edge Processing Pipeline
Request → Edge Platform │ ├── CDN Cache Check (1ms) │ │ │ └── Cache miss? ↓ │ ├── Edge Function Process (10ms) │ │ │ ├── Auth check │ ├── Rate limiting │ ├── Data transformation │ └── Cache result │ └── Response (12ms total)Pattern 3: Hybrid with Origin
┌──────────────┐ ┌──────────────┐ ┌──────────────┐│ User │────▶│ Edge │────▶│ Origin ││ │ │ Platform │ │ Server ││ │◀────│ │◀────│ │└──────────────┘ └──────────────┘ └──────────────┘ │ ├── CDN: Cache origin responses ├── Edge: Process before/after origin └── Both: Reduce origin loadPerformance Metrics
CDN Performance
| Metric | Typical | Target |
|---|---|---|
| Cache hit ratio | 85-98% | >95% |
| Cache hit latency | 1-5 ms | <5 ms |
| Cache miss latency | 50-500 ms | <200 ms |
| Origin offload | 80-99% | >90% |
Edge Computing Performance
| Metric | Typical | Target |
|---|---|---|
| Cold start | 1-50 ms | <10 ms |
| Function execution | 1-100 ms | Varies |
| Memory limit | 128 MB - 8 GB | N/A |
| CPU limit | 0.5 - 4 vCPU | N/A |
Cost Comparison
CDN Pricing Model
| Provider | Bandwidth Cost | Request Cost |
|---|---|---|
| Typical CDN | $0.02-0.12/GB | $0.0075-0.02/10K requests |
| Volume discounts | Available | Available |
Edge Computing Pricing Model
| Provider | Compute Cost | Memory Cost | Duration |
|---|---|---|---|
| Typical Edge | $0.0000002-0.000001/GHz-sec | Included | Per ms |
| Container | $0.01-0.05/hour | Per GB | Hourly |
Rule of thumb: CDN is cheaper for static content delivery. Edge computing is necessary for dynamic processing but costs more per request.
Common Mistakes and Fixes
Mistake: Using edge compute for static content Fix: Use CDN caching for static assets; reserve edge compute for dynamic processing
Mistake: Not caching CDN-eligible responses Fix: Add appropriate cache headers to API responses that can be cached
Mistake: Ignoring cache hit ratio Fix: Monitor cache hit ratio; optimize cache keys and TTLs to maximize hits
Mistake: Running compute-heavy workloads at edge Fix: Use edge for latency-sensitive processing; move heavy compute to cloud
Mistake: Not using both together Fix: Implement hybrid architecture—CDN for caching, edge compute for logic, origin for storage
Frequently Asked Questions
What is the main difference between edge computing and CDN? Edge computing runs application code and processes data at the edge. CDN caches and serves static content from edge locations. Edge computing provides general-purpose compute; CDN provides specialized content delivery.
Can a CDN run code? Some CDNs offer limited compute capabilities through Edge Workers or similar services. However, these are more constrained than full edge computing platforms, with limits on execution time, memory, and available languages.
Do I need both edge computing and CDN? Most modern applications benefit from both. Use CDN for static content delivery and edge computing for dynamic processing. Many platforms offer both capabilities integrated.
Which is faster: edge computing or CDN? For static content, CDN is faster (1-5ms cache hits). For dynamic processing, edge computing adds minimal overhead (5-15ms) compared to origin round-trips (50-500ms). Both dramatically outperform origin-only architectures.
How do I decide between edge computing and CDN? Use CDN for content that can be pre-computed and cached (images, videos, static files). Use edge computing for requests requiring real-time processing (APIs, personalization, AI inference).
Can edge computing cache content like a CDN? Yes, edge computing platforms often include caching capabilities. However, specialized CDNs are optimized for cache hit ratio and content delivery at scale.
What is an Edge Worker? An Edge Worker is a limited compute environment within a CDN that executes JavaScript or WebAssembly at the edge. It’s useful for simple request/response modification but has constraints on execution time and memory.
How does pricing differ? CDNs charge primarily for bandwidth (data transfer) with some request-based pricing. Edge computing charges for compute time (duration × memory) plus data transfer. CDN is typically cheaper for high-volume static content delivery.
Can I use edge computing for video streaming? Edge computing can process video (transcoding, packaging) but CDNs are optimized for streaming delivery. Use edge compute for processing and CDN for delivery in a video pipeline.
How do edge computing and CDN work together? In an integrated platform, CDN handles static content and caching while edge computing handles dynamic logic. A single request might hit CDN cache first, then route to edge compute if cache misses, then finally to origin if needed.
How This Applies in Practice
Modern web applications use both CDN and edge computing in concert. The CDN layer caches static assets and API responses where possible. The edge computing layer handles authentication, personalization, and request transformation. This hybrid approach minimizes latency while enabling dynamic functionality.
Consider an e-commerce platform:
- CDN: Product images, CSS, JavaScript, cached product pages
- Edge compute: Authentication, cart updates, real-time pricing, A/B testing
- Origin: Inventory database, checkout processing, order history
How to Implement on Azion
Azion provides an integrated edge platform with both CDN and edge computing:
- Enable CDN Caching: Configure cache rules for static assets and cacheable API responses
- Deploy Edge Functions: Write Functions for request processing, authentication, and personalization
- Configure Edge Applications: Create Applications that combine caching and compute
- Set Up Edge Origins: Connect to your origin servers for cache misses and dynamic data
Azion’s unified platform handles both content delivery and compute workloads at the edge, with integrated security, observability, and global distribution.
Learn more in the Azion Documentation.
Related Resources
- What is Edge Computing?
- Edge Computing vs Cloud Computing
- What is a CDN?
- What is Caching?
- What is an API Gateway?
Sources:
- CDN Alliance. “State of the CDN Industry Report.” 2025.
- Gartner. “Market Guide for Edge Computing Platforms.” 2025.
- IEEE. “Edge Computing: Vision and Challenges.” 2024.
- Web Almanac. “CDN Usage Statistics.” 2024.