CDN Setup for Mobile App Content Delivery
A user in Novosibirsk opens your app, but the avatar takes 3 seconds to load — the request traverses to a server in Amsterdam. RTT 150 ms, plus origin response time — the cumulative latency kills UX. A CDN caches static content on edge nodes, shortening data paths. For a mobile app with rich media, this cuts load times by 3–10x. Over 5+ years, we have configured CDN for 30+ projects — from fintech apps to streaming services, achieving cache hit ratios of 94% on average and reducing origin load by up to 80%. Our certified engineers guarantee a seamless CDN integration with an SLA of 99.9% uptime.
Why CDN Is Critical for Mobile Apps
Without a CDN, every request to static assets (images, videos, OTA updates) hits the origin server, possibly thousands of kilometers distant. A CDN replicates files across POP (Point of Presence) nodes, minimizing physical distance. For a 5 MB video, the disparity between a 200 ms load and a 1.5 second load is unacceptable. Additionally, CDNs provide DDoS protection (e.g., Cloudflare) and slash origin load by up to 80%, potentially saving $500/month in server costs for a mid-size app with 100k users. Our approach follows industry best practices and guarantees a proven track record.
What to Cache via CDN
CDN is effective for:
- Images, avatars, videos, PDFs, OTA updates, Asset Bundles.
- Dynamic API requests are not cached in standard configuration — use API Gateway or Edge Functions for them.
- Personal data (documents, private photos) through a public CDN with long TTL risks leakage. Use Signed URLs with short lifetimes (1 minute to 1 hour).
Choosing a CDN Provider
| Provider | Strengths | When to Choose |
|---|---|---|
| Cloudflare CDN | Free tier, simple setup, DDoS protection | Startup, limited budget |
| AWS CloudFront | Native integration with S3, Lambda@Edge | Infrastructure already on AWS |
| Google Cloud CDN | Integration with GCS, GKE | Infrastructure on GCP |
| BunnyCDN | Low price, good speed in CIS | Target audience in CIS, cost matters |
| Fastly | Edge computing, Varnish under the hood | Complex caching rules needed |
For audiences in Russia and CIS, check for POP nodes in Moscow and Saint Petersburg. BunnyCDN and Cloudflare have nodes there. According to BunnyCDN documentation, BunnyCDN is up to 40% faster than Cloudflare for CIS users due to optimized BGP routing and edge compute capabilities.
How to Configure Caching in 3 Steps
- Determine content type and TTL. For avatars: 1–24 hours with versioning (query string or path). For static files (icons, fonts): 30–365 days with hash in filename. For video: Range requests with TTL 1–7 days.
-
Set Cache-Control headers. Example:
Cache-Control: public, max-age=2592000, immutable. Theimmutableflag eliminates freshness checks until expiration, reducing origin requests. -
Optimize client-side caching. On Android:
OkHttpwithCacheof 100 MB on disk +CacheControl. On iOS:URLCachewithdiskCapacity100 MB, policyreturnCacheDataElseLoad. Implement origin shield to create a cache hierarchy, further improving hit rates.
Invalidation and Purge
CDN caches by URL. Changing a file without altering the URL leaves the cache stale until TTL expires. Three approaches:
- Versioned URLs (
/assets/logo-a1b2c3d4.png) — best, no manual purge required. - Query string version (
/assets/logo.png?v=42) — simpler, but some CDNs ignore query strings. - Manual purge via API — for urgent replacements. Integrate into CI/CD pipelines; our engineers provide a certified script for AWS CloudFront or Cloudflare.
Example CDN Integration in CI/CD
After build, a new artifact with a hash is uploaded to S3. The CloudFront distribution automatically picks up the file through the origin. If urgent invalidation is needed, the pipeline executes `aws cloudfront create-invalidation`. We guarantee this process is documented and repeatable.Monitoring and Metrics
After setup, we monitor:
- Cache Hit Ratio — target 90%+. If below 90%, either shorten TTL or check URL uniqueness. Across 30+ projects, the average is 94%.
- Bandwidth savings — the amount of traffic served by CDN instead of origin (up to 70% savings, equating to ~$300/month savings for a typical app).
- P95 latency by region — ensure target markets receive acceleration. For CIS, target P95 latency is <100 ms.
In the mobile app, log the X-Cache header (if your CDN provides it) — this gives real hit rate from the client's perspective.
What's Included in Turnkey CDN Setup
- Audit of current architecture and provider selection (guaranteed RCA within 2 days).
- Caching configuration and purge rules setup.
- Integration of Signed URLs for protected content.
- Mobile client optimization (OkHttp/URLCache).
- Monitoring and cache hit ratio report.
- Documentation and team training.
- Post-launch support with 24/7 SLA.
Timeline and Cost
Basic configuration: 1–2 business days. Complex scenarios (Edge Functions, geo-routing, Signed URLs): 3–5 days. Cost is calculated individually — a typical basic setup starts at $500, while complex integrations can reach $2,000. Contact us for a project assessment. Get a consultation from a certified engineer with 5+ years of experience.
Cloudflare CDN — official documentation.