Forward & Reverse Proxy
Networking & DeliveryAn intermediary that forwards requests on behalf of a client (forward proxy) or on behalf of a server (reverse proxy) — the conceptual ancestor of load balancers, API gateways, and CDNs.
A proxy sits between two parties and relays traffic. A forward proxy sits in front of clients and represents them to the outside world (a corporate proxy hiding many employees behind one egress IP, or a VPN); a reverse proxy sits in front of servers and represents them to the outside world (clients think they're talking to 'the server', but they're actually talking to the proxy, which forwards to one of many real backends). Nearly every 'traffic management' component in this library — load balancers, API gateways, CDNs — is a specialized reverse proxy with extra features bolted on, which is exactly the kind of unifying insight interviewers like to hear.
How it connects
Forward & Reverse Proxy as the source, with the components it typically interacts with.
- → Load Balancer: A reverse proxy commonly implements load balancing as one of its responsibilities, or sits directly in front of a dedicated LB.
- → API Gateway: An API gateway is a specialized reverse proxy with added concerns (auth, rate limiting, routing by API contract).
- → CDN (Content Delivery Network): CDN edge nodes function as reverse proxies, terminating client connections and forwarding cache misses to an origin.
- → Service Mesh & Sidecar Proxy: In microservices, sidecar proxies (Envoy) act as per-service reverse proxies, and a service mesh is the control plane coordinating all of them.