Reverse Proxy vs Load Balancer Which One Should You Choose

When designing scalable and reliable backend architectures, two common components are Reverse Proxies and Load Balancers. While they share similarities in handling network traffic, they serve different purposes.

This article explains the differences, use cases, and when to use each.

A Reverse Proxy is an intermediary server that sits between clients and backend servers, forwarding client requests to the appropriate server.

• Request Forwarding - Directs client requests to backend servers.
• SSL Termination - Handles encryption/decryption of HTTPS traffic.
• Caching - Stores frequently requested content to reduce server load.
• Security - Hides backend server IPs and blocks malicious traffic.
• Compression & Optimization - Compresses responses to improve performance.

graph TD;
    Client1 -->|Request| ReverseProxy;
    Client2 -->|Request| ReverseProxy;
    ReverseProxy -->|Forwards Request| Server1;
    ReverseProxy -->|Forwards Request| Server2;
    Server1 -->|Response| ReverseProxy;
    Server2 -->|Response| ReverseProxy;
    ReverseProxy -->|Sends Response| Client1;
    ReverseProxy -->|Sends Response| Client2;

A Load Balancer distributes network traffic across multiple servers to improve performance and ensure availability. It operates at Layer 4 (TCP/UDP) or Layer 7 (HTTP/HTTPS).

• Traffic Distribution - Spreads requests across multiple servers.
• Failover & High Availability - Redirects traffic when a server fails.
• Session Persistence - Ensures a user stays connected to the same server.
• Health Checks - Monitors server health and removes failed nodes.

graph TD;
    Client1 -->|Request| LoadBalancer;
    Client2 -->|Request| LoadBalancer;
    LoadBalancer -->|Routes Traffic| Server1;
    LoadBalancer -->|Routes Traffic| Server2;
    LoadBalancer -->|Routes Traffic| Server3;
    Server1 -->|Response| LoadBalancer;
    Server2 -->|Response| LoadBalancer;
    Server3 -->|Response| LoadBalancer;
    LoadBalancer -->|Sends Response| Client1;
    LoadBalancer -->|Sends Response| Client2;

Use a Reverse Proxy if:

• You need to protect backend servers from direct exposure.
• You require SSL termination to offload encryption work.
• Your application benefits from caching frequently accessed content.
• You need traffic filtering, compression, or security enhancements.

Use a Load Balancer if:

• You need to distribute traffic across multiple servers.
• Your application requires high availability and failover mechanisms.
• You want to optimize performance by spreading requests evenly.
• Your system involves multiple identical backend servers handling requests.

Yes, many architectures use both a Reverse Proxy and a Load Balancer:

• The Load Balancer distributes requests among multiple Reverse Proxies.
• Each Reverse Proxy then routes requests to backend services while providing security and caching.

graph TD;
    Client -->|Request| LoadBalancer;
    LoadBalancer -->|Distributes to| ReverseProxy1;
    LoadBalancer -->|Distributes to| ReverseProxy2;
    ReverseProxy1 -->|Routes to| ServerA;
    ReverseProxy1 -->|Routes to| ServerB;
    ReverseProxy2 -->|Routes to| ServerC;
    ReverseProxy2 -->|Routes to| ServerD;
    ServerA -->|Response| ReverseProxy1;
    ServerB -->|Response| ReverseProxy1;
    ServerC -->|Response| ReverseProxy2;
    ServerD -->|Response| ReverseProxy2;
    ReverseProxy1 -->|Returns Data| LoadBalancer;
    ReverseProxy2 -->|Returns Data| LoadBalancer;
    LoadBalancer -->|Response| Client;

• Reverse Proxies protect backend services, optimize performance, and provide security features like SSL termination and caching.
• Load Balancers focus on traffic distribution, ensuring scalability and high availability.
• Many architectures use both for optimal performance and security.

By understanding their roles, you can design a more scalable, secure, and efficient backend system.