Load Balancer

A device that acts as a reverse proxy and distributes network or application traffic across a number of servers.

A load balancer is a device or software component that distributes incoming network traffic across multiple backend servers or services. The primary goals are to maximize throughput, minimize response time, avoid overloading any single server, and provide redundancy in case of server failure.

Load balancing algorithms include round-robin (distributing requests sequentially), least connections (routing to the server with fewest active connections), weighted distribution (routing based on server capacity), and IP hash (routing based on client IP for session persistence). Load balancers can operate at Layer 4 (TCP/UDP) or Layer 7 (HTTP/HTTPS), with Layer 7 offering content-aware routing decisions.

In API architectures, load balancers work alongside or are integrated into API gateways. While traditional load balancers focus on distributing traffic, API gateways add application-level concerns like authentication, rate limiting, and request transformation. Serverless platforms and edge-deployed gateways typically include built-in load balancing, automatically distributing requests across available compute resources without manual configuration.