# Proxy Server

URL: https://softwaredictionary.org/terms/proxy-server
Category: Networking
Last updated: 2026-09-30
In Turkish: Proxy Sunucusu

In short: A proxy server is an intermediary that receives network requests on behalf of clients or servers and passes them on, adding control, caching, or privacy.

## What is a proxy server?

A proxy server sits between two parties in a network conversation and relays traffic between them. Instead of connecting directly to a website, a client sends its request to the proxy, which makes the request itself and passes the response back. Because all traffic flows through it, the proxy can log, filter, cache, or modify requests and responses.

The key distinction is whose side the proxy is on. A forward proxy works for clients: it sits in front of a group of users, such as a company network, and sends their requests out to the internet, so websites see the proxy's IP address rather than each user's. A reverse proxy works for servers: it sits in front of one or more backend servers, receives requests from the internet, and forwards them inside, often handling TLS, caching, compression, and load balancing so clients never talk to the backends directly.

Think of a forward proxy as a personal assistant who places calls on your behalf, and a reverse proxy as a company switchboard that answers every incoming call and routes it to the right department. Organizations use forward proxies to enforce browsing policies, cache common downloads, and log outbound traffic, and developers often configure one through the `HTTP_PROXY` and `HTTPS_PROXY` environment variables. Load balancers, API gateways, and CDNs are all built on the reverse proxy idea.

A proxy is often confused with a VPN. A typical proxy handles traffic for specific applications or protocols, such as a browser's HTTP requests, and doesn't necessarily encrypt it, while a VPN routes all of a device's traffic through an encrypted tunnel. For HTTPS, a forward proxy usually just opens a tunnel with the HTTP `CONNECT` method and can't read the encrypted content, unless it is set up to intercept TLS with its own trusted certificate.

## Key takeaways

- A proxy server relays requests and responses between clients and servers.
- A forward proxy acts for clients and hides their IP addresses from the sites they visit.
- A reverse proxy acts for servers and hides the backend servers from clients.
- Proxies can cache, filter, log, and modify the traffic that passes through them.
- Unlike a VPN, a proxy usually covers specific apps or protocols and may not encrypt traffic.

## Example: Sending requests through a forward proxy

```bash
# Send one request through a forward proxy
curl -x http://proxy.internal.example:3128 https://example.com

# Or set the proxy for every tool that honors these environment variables
export HTTP_PROXY="http://proxy.internal.example:3128"
export HTTPS_PROXY="http://proxy.internal.example:3128"
export NO_PROXY="localhost,127.0.0.1,.internal.example"  # skip the proxy for these

curl https://example.com  # now goes through the proxy automatically
```

## Frequently asked questions

**What is the difference between a forward proxy and a reverse proxy?**

A forward proxy sits in front of clients and makes requests to the internet on their behalf, hiding who the clients are. A reverse proxy sits in front of servers and receives requests from the internet on their behalf, hiding which backend server actually handles each request.

**What is the difference between a proxy and a VPN?**

A proxy usually relays traffic for specific applications, such as a browser, and may not encrypt it. A VPN routes all of a device's traffic through an encrypted tunnel to the VPN server.

**Can a proxy server see my HTTPS traffic?**

A normal forward proxy can see which host you connect to, but not the encrypted content, because it only tunnels the TLS connection. Some corporate proxies decrypt and inspect HTTPS traffic by installing their own trusted certificate on employees' devices.

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Software Dictionary: https://softwaredictionary.org/ · https://softwaredictionary.org/llms.txt