How do I send different API traffic to different backends by region?

A common way to do this is to put a global entry layer in front of your APIs, then route requests to different backends based on the caller’s region.

Typical patterns

1) DNS / Geo-DNS routing

Use a DNS service that returns different IPs depending on where the client is located.

• Pros: Simple, fast, works well for coarse routing
• Cons: Based on resolver location, not always the actual client; limited request-level control

Example:

• US clients → api-us.example.com
• EU clients → api-eu.example.com
• Asia clients → api-apac.example.com

2) Global load balancer / CDN / edge routing

Use a global traffic manager that inspects geography and forwards to the nearest or designated backend.

Examples:

• AWS Route 53 Geo/Latency routing + ALB/NLB
• Cloudflare Load Balancing
• Azure Front Door
• Google Cloud Load Balancing

This is usually the best approach if you want:

• region-based failover
• low latency
• centralized TLS and security
• health checks

3) API Gateway with routing rules

If your API gateway supports header/geo-based routing, you can route by:

• X-Region header
• JWT claim / tenant region
• path prefix like /eu/*, /us/*
• geolocation from source IP

Examples:

• Kong
• Apigee
• NGINX / Envoy
• AWS API Gateway + Lambda/ALB behind it

4) Application-level routing

Your API service inspects the request and proxies or dispatches internally to the right backend.

• Pros: Maximum flexibility
• Cons: More code, more complexity, harder to scale/operate

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Recommended design

For most production systems:

1. Put a global traffic manager in front.
2. Route requests using:
   • client region, or
   • tenant region, or
   • explicit region header.
3. Back each region with its own backend stack.
4. Add health checks and failover rules.
5. Keep data residency requirements in mind.

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Important considerations

Region source

Decide where the “region” comes from:

• GeoIP from client IP
• User preference
• Tenant/account region
• Requested region header

If you need strict control, don’t rely only on GeoIP.

Data residency

If you’re handling regulated data, make sure:

• EU traffic stays in EU
• logs/metrics don’t accidentally cross regions
• backups and replicas follow compliance rules

Failover

Have a plan for:

• region down
• partial outage
• rerouting to a backup region

Consistency

If users can hit multiple regions, think about:

• sticky sessions
• database replication
• cache coherence
• eventual consistency

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Example: simple region routing rule

• If request comes from Europe → send to eu-backend
• If request comes from North America → send to us-backend
• Otherwise → send to global-backend

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If you want, I can show you how to implement this on a specific platform like AWS, GCP, Azure, Cloudflare, Kong, or NGINX.