A reverse proxy is a server that sits between external clients and one or more origin servers, intercepting incoming requests and forwarding them on behalf of those backend servers. From the client's perspective, it appears to be communicating directly with the destination server, while in reality the reverse proxy is managing the connection behind the scenes.
The term "reverse" distinguishes it from a forward proxy, which acts on behalf of clients to reach external servers. A reverse proxy does the opposite: it acts on behalf of servers to handle incoming client traffic. This positional difference has significant implications for how web infrastructure is designed and secured.
How a Reverse Proxy Works
When a user's browser sends a request to a website, that request first reaches the reverse proxy rather than the application server directly. The proxy evaluates the request and routes it to the appropriate backend server, then returns the server's response to the client. This entire process is transparent to the end user.
Because every request passes through the reverse proxy, it becomes a natural control point for several critical infrastructure functions. Load balancing is one of the most common uses: the proxy distributes incoming traffic across multiple backend servers, preventing any single server from becoming overwhelmed and improving overall availability. This is conceptually similar to how a load balancer operates, and in practice many reverse proxies serve as load balancers simultaneously.
Common Use Cases
Caching is another major benefit. A reverse proxy can store copies of frequently requested responses and serve them directly to subsequent users without involving the origin server at all. This reduces server load and decreases response times, functioning in a way that overlaps with what a CDN provides at a global scale.
SSL termination is also frequently handled at the reverse proxy layer. Rather than configuring every backend server to manage encrypted HTTPS connections independently, the proxy decrypts incoming SSL/TLS traffic and forwards plain HTTP requests internally. This centralizes certificate management and reduces the computational overhead on individual application servers.
Reverse proxies also provide a layer of security by concealing the identity and structure of backend infrastructure. Since clients never interact with origin servers directly, internal IP addresses and server configurations remain hidden from the public internet. This makes it significantly harder for attackers to target specific servers.
Popular software implementations include Nginx, HAProxy, and Apache HTTP Server configured in proxy mode. Cloud providers and CDN platforms such as Cloudflare also operate as reverse proxies at massive scale. For any web application serving meaningful traffic, a reverse proxy is a foundational component of reliable, performant, and secure infrastructure.