What Is a Reverse Proxy?
A reverse proxy is a server that sits in front of one or more backend servers and forwards client requests to them. From the client's point of view, it looks like a single server is handling everything; in reality the reverse proxy is receiving each request, deciding which backend should answer, and relaying the response back. It is one of the most common building blocks of modern web infrastructure.
How a Reverse Proxy Works
The reverse proxy is the public-facing endpoint: clients connect to it, not to the application servers directly. When a request arrives, the proxy forwards it to an appropriate backend on a private network, receives the backend's response, and returns it to the client. Because the backends are hidden behind the proxy, their addresses and internal structure are never exposed to the outside world.
Reverse Proxy vs. Forward Proxy
The two are mirror images, and the direction is what separates them. A forward proxy sits in front of clients and acts on their behalf — a corporate web filter that all employee traffic passes through is a classic example. A reverse proxy sits in front of servers and acts on their behalf. A forward proxy hides who is making the request; a reverse proxy hides what is answering it.
Common Uses of a Reverse Proxy
- Load balancing: spreading requests across several backend servers so no single one is overwhelmed.
- SSL/TLS termination: handling HTTPS encryption in one place so backends can speak plain HTTP internally.
- Caching: storing frequently requested content to reduce load and speed up responses.
- Security: hiding the origin servers, filtering malicious traffic, and enforcing rate limits.
- Routing: serving several applications or microservices under one domain and port.
Popular Reverse Proxy Software
Widely used reverse proxies include Nginx, HAProxy, the Apache HTTP Server (with mod_proxy), Envoy, and Traefik. Cloud platforms provide managed equivalents such as Cloudflare and AWS Elastic Load Balancing. The right choice depends on whether you mainly need raw performance, rich routing rules, or tight integration with a container platform like Kubernetes.
Reverse Proxy and Load Balancing
The two concepts overlap, which is a frequent source of confusion. A load balancer is essentially a reverse proxy whose main job is distributing traffic across multiple servers, usually with health checks and a balancing algorithm. A reverse proxy is the broader idea: it may load balance, but it may also simply cache, terminate SSL, or route requests for a single backend. In practice the same piece of software often performs both roles at once. A useful rule of thumb is that every load balancer is a kind of reverse proxy, but not every reverse proxy is a load balancer — a proxy that fronts one backend purely to add caching and HTTPS is still a reverse proxy even though it balances nothing.
A reverse proxy is closely tied to other infrastructure pieces — see how a load balancer distributes traffic, how a CDN caches content at the edge, and why HTTPS termination matters.
Frequently Asked Questions
They overlap heavily. A load balancer specifically distributes incoming traffic across multiple backend servers using health checks and a balancing algorithm. A reverse proxy is the more general concept of a server that fronts your backends — it may load balance, but it can also cache, terminate SSL, or route a single service. Many tools, such as Nginx and HAProxy, act as both.
A forward proxy sits in front of clients and forwards their outbound requests to the internet, often for filtering or anonymity. A reverse proxy sits in front of servers and handles inbound requests on their behalf. The difference is which side it represents: the client (forward) or the server (reverse).
To centralize SSL/TLS handling, balance load across servers, cache content for speed, hide and protect your origin servers, and route requests for many services through one entry point. It lets you change or scale the backend without clients ever noticing.