This is a very common confusion because Forward Proxy, Reverse Proxy, and API Gateway all sit "in the middle" of communication. The difference is who they represent and what additional functionality they provide.
1. Forward Proxy: A Forward Proxy sits in front of the client and acts on behalf of the client.
Client --> Forward Proxy --> Internet Server
The server thinks: "This request came from the proxy."
Example: Suppose your company blocks access to social media.
The company proxy can:
- Allow/block websites
- Cache responses
- Hide your IP address
- Log your traffic
Real-world examples: Company Proxies and VPN Servers
2. Reverse Proxy: A Reverse Proxy sits in front of the servers and acts on behalf of the servers.
Client --> Reverse Proxy --> Backend Servers
The client thinks: "I am talking to one server."
But behind the proxy, there may be many servers.
Example
Internet
|
v
NGINX
|
+--> App Server 1
+--> App Server 2
+--> App Server 3
Responsibilities:
- Load balancing
- SSL termination
- Caching
- Compression
- Routing
Examples: Nginx
3. API Gateway: An API Gateway is a specialized reverse proxy for APIs and microservices.
Client
|
v
API Gateway
|
+--> User Service
+--> Order Service
+--> Payment Service
It does everything a reverse proxy does plus:
- Authentication
- Authorization
- Rate limiting
- API versioning
- Request transformation
- Response aggregation
- Monitoring
- API keys
- Quotas
Why Definitions Sound Similar? Because all of them:
- Receive requests
- Forward requests
- Return responses
The real difference is:
Question Forward Proxy Reverse Proxy API Gateway
Represents whom? Client Server Server/API
Sits in front of? Clients Servers APIs/Microservices
Used by? Internal users Backend systems Microservices
Authentication? Rare Sometimes Yes
Rate limiting? Rare Sometimes Yes
Aggregation? No No Yes
One-line way to remember
Forward Proxy → protects and represents clients.
Reverse Proxy → protects and represents servers.
API Gateway → a smart reverse proxy specifically for APIs and microservices.