Reverse Proxy vs Load Balancer — What's The Difference?

Modern applications and websites handle large amounts of traffic. Two of the main instruments to ensure the smooth operation of large-scale systems are load balancers and reverse proxies.

However, they approach traffic management in slightly different ways:

𝗟𝗼𝗮𝗱 𝗯𝗮𝗹𝗮𝗻𝗰𝗲𝗿𝘀 are concerned with routing client requests across multiple servers to 𝗱𝗶𝘀𝘁𝗿𝗶𝗯𝘂𝘁𝗲 𝗹𝗼𝗮𝗱 and 𝗽𝗿𝗲𝘃𝗲𝗻𝘁 𝗯𝗼𝘁𝘁𝗹𝗲𝗻𝗲𝗰𝗸𝘀. This helps maximize throughput, reduce response time, and optimize resource use.

𝗟𝗼𝗮𝗱 𝗯𝗮𝗹𝗮𝗻𝗰𝗲𝗿 𝗶𝗻 𝗮𝗰𝘁𝗶𝗼𝗻:

𝟭) Client requests are sent to the load balancer instead of directly to the server(s) hosting the application. 𝟮) A server is chosen from the load balancer's list using a predetermined algorithm. 𝟯) The request is forwarded to the selected server. 𝟰) The server processes the requests and sends the response back to the load balancer. 𝟱) The load balancer forwards the response to the client.

A 𝗿𝗲𝘃𝗲𝗿𝘀𝗲 𝗽𝗿𝗼𝘅𝘆 is a server that sits between external clients and internal applications. While reverse proxies can distribute load as a load balancer would, they provide advanced features like SSL termination, caching, and security. Reverse proxies are 𝗺𝗼𝗿𝗲 𝗰𝗼𝗻𝗰𝗲𝗿𝗻𝗲𝗱 𝘄𝗶𝘁𝗵 𝗹𝗶𝗺𝗶𝘁𝗶𝗻𝗴 𝗮𝗻𝗱 𝘀𝗮𝗳𝗲𝗴𝘂𝗮𝗿𝗱𝗶𝗻𝗴 𝘀𝗲𝗿𝘃𝗲𝗿 𝗮𝗰𝗰𝗲𝘀𝘀.

Whilst load balancers and reverse proxies possess distinct functionalities, in practice the lines can blur, as many tools act as both a load balancer and reverse proxy. For example, tools like Nginx can perform both roles depending on their configuration.