Reverse Proxy vs API Gateway vs Load Balancer

Reverse Proxy vs API Gateway vs Load Balancer

what's the difference?

These three often overlap in implementation, but they serve different layers of responsibility in system design.

1) Reverse Proxy

Core role: Traffic mediator in front of backend servers

What it does

• Receives client requests → forwards to backend servers
• Hides internal services (security boundary)
• Can do: SSL termination Caching Compression Basic routing (path-based)

Think of it as:

“A smart middleman sitting in front of servers”

Example tools

• Nginx
• Apache HTTP Server

Example flow

Client → Reverse Proxy → Backend Service        

2) Load Balancer

Core role: Distribute traffic across multiple servers

What it does

• Spreads incoming requests across instances
• Prevents overload on a single server
• Ensures high availability + scalability

Types

• L4 (Transport layer) → TCP/UDP (fast, less intelligent)
• L7 (Application layer) → HTTP-aware (can route by URL, headers)

Think of it as:

“Traffic distributor ensuring no server gets overwhelmed”

Example tools/services

• HAProxy
• AWS Elastic Load Balancer

Example flow

Client → Load Balancer → Multiple Servers        

3) API Gateway

Core role: Entry point for microservices + API management

What it does (much richer layer)

• Routes requests to correct microservice
• Handles: Authentication / Authorization (JWT, OAuth) Rate limiting Request/response transformation Aggregation (combine multiple service calls) API versioning

Think of it as:

“A control center for all APIs”

Example tools

• Kong
• AWS API Gateway

Example flow

Client → API Gateway → Microservices (User, Order, Payment)        

Key Differences (Concise)

How They Relate (Important)

They are not mutually exclusive — often used together:

Typical modern architecture

Client
  ↓
Load Balancer
  ↓
Reverse Proxy / API Gateway
  ↓
Microservices        

Or in cloud:

Client → API Gateway → Load Balancer → Services        

Simple Analogy

• Load Balancer → Traffic police (distributes cars)
• Reverse Proxy → Security gate (controls entry)
• API Gateway → Reception + manager (auth, routing, rules)

When to Use What

• Use Load Balancer → when you have multiple instances
• Use Reverse Proxy → when you need central entry + basic control
• Use API Gateway → when building microservices / public APIs