A proxy sits between a client and a server. A forward proxy acts for the client. A reverse proxy acts for the server.

The client routes traffic through a proxy that hides the client’s identity from the server.

flowchart LR
    Client["👤 Client<br/>Real IP: 1.2.3.4"] --> FP["Forward Proxy"]
    FP --> Server["🌐 Server<br/>Sees proxy IP: 5.6.7.8"]
    FP --> Blocked["🚫 Blocked sites"]

    style Client fill:#7c3aed,color:#fff
    style FP fill:#4f46e5,color:#fff
    style Server fill:#059669,color:#fff
    style Blocked fill:#dc2626,color:#fff

Uses: Bypass geo-restrictions, employee web filtering, anonymity.

The server hides behind a proxy that receives all client requests.

flowchart LR
    Client["👤 Client"] --> RP["Reverse Proxy<br/>(Nginx, HAProxy)"]
    RP --> LB["Load Balancer"]
    RP --> Cache["Cache (optional)"]
    RP --> Auth["Auth Check"]
    RP --> S1["Server 1"]
    RP --> S2["Server 2"]
    RP --> S3["Server 3"]

    style Client fill:#7c3aed,color:#fff
    style RP fill:#059669,color:#fff
    style S1 fill:#6366f1,color:#fff
    style S2 fill:#6366f1,color:#fff
    style S3 fill:#6366f1,color:#fff

What a reverse proxy can do:

• Load balancing — distribute requests
• Caching — serve cached responses
• SSL termination — decrypt HTTPS
• Rate limiting — throttle clients
• Compression — gzip responses
• Static file serving — serve assets directly

An API Gateway is a specialized reverse proxy for microservices that adds routing, auth, and aggregation.

• Adding a proxy adds a hop → slight latency.
• The reverse proxy / API gateway is a potential SPOF — run multiple.
• API gateways can become a bottleneck if they do too much processing.

• Forward proxy hides the client (used for privacy/browsing).
• Reverse proxy hides the server (used for scaling/security).
• API Gateway = reverse proxy on steroids: routing, auth, rate limiting, aggregation.