What Is a Proxy Server? How It Works, Types, Uses

A proxy server is an intermediary computer that sits between your device and the internet: you send your request to the proxy, the proxy makes the request to the website for you, and then it passes the response back. MDN defines a proxy as an intermediate program or computer that may forward requests, serve them from a cache, or modify them along the way. To the website, the request comes from the proxy's IP address instead of yours, which is why proxies are used for privacy, access control, caching and large-scale data collection. This guide explains how proxies work, the main types, what they are used for, and what they do not do.

How a Proxy Server Works

Without a proxy, your device connects straight to a website, which sees your IP address. With a forward proxy, the flow adds one hop:

1. Your browser or app is configured to send traffic to the proxy.
2. The proxy checks who you are, if it requires authentication, and applies any rules.
3. The proxy opens its own connection to the website and sends your request.
4. The website responds to the proxy, which returns the response to you.

For HTTPS sites, your client asks the proxy to open a tunnel with the CONNECT method and then talks TLS to the website through it, so the proxy relays encrypted data it cannot read. If the proxy needs credentials, it answers 407 and you supply them in a Proxy-Authorization header. Our guide to HTTP proxies and CONNECT shows the details.

What a Website Sees With and Without a Proxy

Some proxies add headers such as Via or X-Forwarded-For that reveal they are proxies or even your original IP, which is why "transparent" proxies are not for anonymity.

Forward Proxies and Reverse Proxies

There are two basic directions. A forward proxy acts for clients: you configure your device to use it, and it hides the client from the websites it visits. A reverse proxy acts for servers: it sits in front of a website, receives visitors' requests and forwards them to the real servers behind it, hiding them and often caching or balancing load. Everything in this article is about forward proxies unless stated; see what a reverse proxy is for the other direction.

Types of Proxy Servers by Protocol

• HTTP and HTTPS proxies understand web traffic and handle most browsing, scraping and API work.
• SOCKS5 proxies relay arbitrary TCP connections and suit non-web traffic and some applications. See HTTP vs SOCKS5.

Types of Proxy Servers by IP Source

For anyone buying a proxy, the source of the IP address matters most, because it decides how readily websites accept the traffic:

BuyProxy sells all four, plus IPv6, with per-GB billing; see the proxy type decision guide or the plain-English residential proxy explainer.

What Proxy Servers Are Used For

• Privacy from websites. The site sees the proxy's IP, not yours.
• Access to regional content. Seeing a site as a visitor in another country does.
• Corporate control. Organisations route employee traffic through proxies to filter content, log usage and enforce policy.
• Caching. A proxy can serve repeated requests from its cache, saving bandwidth.
• Web scraping and data collection. Rotating proxies spread requests across many IPs; see proxies for web scraping.
• Testing and verification. Checking localized pages and ads from inside each market.

What a Proxy Does Not Do

A proxy changes the IP address a website sees. By itself it does not encrypt your traffic, hide it from the proxy operator, or cover your whole device: most proxies work per application. If you need device-wide encryption, for example on public Wi-Fi, a VPN is the right tool; see proxy vs VPN. And because you are trusting the proxy operator with your traffic, free proxies are risky: a study of more than 640,600 free proxies found most never responded and thousands tampered with content, covered in are free proxies safe.

How to Set Up a Proxy Server Connection

You do not need to run a proxy to use one. You get a host, port and credentials from a provider and put them in your tool. With curl:

curl -x "http://USER:PASS@HOST:PORT" https://api.ipify.org

The response is the proxy's IP address. Browsers and operating systems have proxy settings, and automation tools such as Puppeteer and Playwright accept a proxy option. To get credentials, see how to buy a proxy server.

How to Choose a Proxy

1. Decide the job and how strictly the target blocks automation.
2. Pick the IP type that fits (datacenter for open targets, residential for protected ones).
3. Choose per-GB or per-IP billing.
4. Buy a small amount, test it and scale only if it works.

Anonymity Levels: Transparent, Anonymous and Elite Proxies

Proxies are often grouped by how much they reveal. The labels are a convention rather than a formal standard, but they are widely used when comparing sellers:

Transparent proxies are typically used by organisations for filtering and caching, not for privacy. For privacy or data collection you want a proxy that does not forward your own address, and even then the IP type matters more than the header level, because websites can recognise datacenter ranges by who owns them.

Explicit and Transparent Deployment

There are two ways traffic ends up at a proxy. With an explicit proxy, the client is configured to use it, either per application or through system settings, and knows it is there. With a transparent (or intercepting) proxy, the network redirects traffic to the proxy without any client configuration, which is how schools and workplaces often enforce content filters. Everything you buy from a proxy provider is an explicit proxy: you put the address and credentials into your own tool.

Common Proxy Ports and URL Formats

A proxy is addressed by host and port, and the port depends on the provider. When credentials are required they are written into a URL of the form scheme://username:password@host:port, where the scheme is http for an HTTP proxy or socks5 for a SOCKS5 proxy. Many tools accept this URL directly, including curl, Python's requests library and Node's undici. If a special character in the password breaks the URL, percent-encode it.

How to Tell Whether You Are Using a Proxy

The simplest check is to ask a service what IP address it sees. Visit an IP-echo service with and without the proxy configured and compare the results, or paste the address into the IP checker to see its location and network. If the address changes to one owned by a different network, your traffic is going through the proxy.

Frequently Asked Questions

Q: What is a proxy server in simple terms?
A middleman between your device and the internet. It sends your requests to websites for you, so the website sees the proxy's IP address instead of yours.

Q: What is a proxy?
A proxy is the same thing as a proxy server: an intermediary that forwards requests. The word is also used for software or services that perform that role.

Q: Is a proxy server safe?
It depends on who runs it. A reputable provider with published terms is generally fine for web tasks, but a proxy operator can see unencrypted traffic, so avoid free proxies for anything sensitive.

Q: Does a proxy server hide my IP address?
It hides your IP from the websites you visit, replacing it with the proxy's IP. The proxy operator still knows your IP, and the proxy does not encrypt your traffic by itself.

Q: What is the difference between a proxy server and a VPN?
A VPN encrypts and tunnels all traffic from your device, while a proxy usually forwards the traffic of one application without adding encryption. See our proxy vs VPN comparison for details.

Summary

A proxy server is an intermediary that makes requests on your behalf, so websites see its IP address instead of yours. Choose the type by how strictly your target blocks automation, remember it does not encrypt your traffic on its own, and buy from an operator you can trust.

Compare and buy proxies on BuyProxy →