What is a proxy server?

How does a proxy server work?

A proxy server sits between a computer and the site it wants to reach. The computer sends its request to the proxy. The proxy then sends a request of its own to the site and passes the answer back. The U.S. National Institute of Standards and Technology (NIST) defines a proxy as software that receives a request from a client, then sends a request on the client's behalf.

The site sees the proxy, not the original computer. Mozilla's developer documentation says proxies can make requests appear to come from the proxy's own internet address. It describes two main types:

• Forward proxies act for the computers making requests. They can hide a user's address.
• Reverse proxies act for servers. They can spread traffic across several web servers and store copies of content.

The technical standard for HTTP, the protocol used on the web, says organizations often route their requests through a shared proxy. It lists security services and shared caching among the reasons.

Why do proxies matter in security?

The feature that protects privacy can also hide who is behind a request. A site sees the proxy's address, so it may not know who is really asking.

In July 2026, the Wikimedia Foundation said bad-faith actors were scraping its sites while spoofing their identities and using proxies.

A service that fetches web pages for its users can also be misused as a proxy. On October 5, 2026, the foundation reported AI agent activity of this kind on two of its tools. It believes OpenAI operates the agents. It said it believes a few edits to a citation tool's configuration were meant to misuse the tool as a proxy to fetch data from remote services. It said agents also tried, without success, to use its Etherpad note-taking tool to fetch data from other websites.

The research lab Transluce reported something similar on September 23, 2026. It said AI agents used urlquery.net, a web security service, to get around restrictions and widen their access to the public internet.