TL;DR: A proxy routes your browser session's traffic through an intermediary server, so the site you visit sees the proxy's IP address and location instead of your own. Browser agents use proxies to get a consistent network identity, to appear in a specific country or city, and to run many sessions without a single shared data-center IP. Browserbase gives every session a built-in residential proxy with proxies: true, and pairs it with Verified for access to protected sites.

When your automation runs from your laptop, the site sees your home IP and your real location. Move that same code to a server and the picture changes, now the traffic comes from a data-center IP that thousands of other requests already share, from wherever the server happens to live. A proxy is how you take control of that network identity instead of leaving it to chance.

What is a proxy?

A proxy is a server that sits between your browser and the website, forwarding your requests and relaying the responses back. The destination site sees the proxy's IP address and inferred location rather than the machine your code actually runs on. That single layer of indirection is what lets you choose where your traffic appears to come from and what network identity it carries.

The IP address is the important part. Every request carries the address it came from, and sites read a lot into that address, its rough geographic location, whether it belongs to a home internet connection or a data center, and how many other requests have recently come from it. A proxy replaces your address with one you chose, so you control the story that address tells.

What kinds of proxies are there?

Proxies are usually grouped by where their IP addresses come from, and that source decides how ordinary a request looks. The three you'll meet most often are residential, data-center, and mobile.

• Residential proxies route through IP addresses assigned to real home internet connections, so a request looks like it came from an ordinary visitor. They are the most broadly usable for reaching everyday websites.
• Data-center proxies route through IPs owned by hosting providers. They are fast and cheap, but many sites recognize data-center ranges and treat that traffic differently.
• Mobile proxies route through cellular network IPs. They are the scarcest and most expensive, used when a task specifically needs to look like a mobile device on a carrier network.

Browserbase's built-in proxies are residential, which is why they work as a general default for reaching everyday sites.

What is a rotating proxy?

A rotating proxy changes the outbound IP address across requests or sessions, drawing from a pool of many addresses rather than reusing one. Rotation spreads your traffic so no single IP carries the whole load, which matters when an agent makes many requests to the same site. The counterpart is a sticky or static proxy, which holds one IP for the length of a session, useful when a site ties your login or cart to the address you started with.

Why does a browser agent need a proxy?

Three reasons come up again and again, and most agents hit at least one of them.

1. Location. Prices, search results, and availability change by country. A proxy lets your agent see a site the way a user in New York, London, or Tokyo would, which is essential for anything region-specific.
2. Consistent network identity. A residential IP looks like an ordinary visitor, where a shared data-center IP stands out. A proxy gives your session an address that fits the traffic a site expects to see.
3. Scale. Running many sessions from one data-center IP concentrates all of that traffic on a single address. Proxies spread it across many, so one busy address doesn't become the reason a site starts refusing you.

How do you add a proxy to a browser session?

On Browserbase, set proxies: true when you create the session. Every request from that session then routes through a managed residential proxy, with no proxy server to run or credentials to manage yourself.

import { Browserbase } from "@browserbasehq/sdk";

const bb = new Browserbase({ apiKey: process.env.BROWSERBASE_API_KEY! });

const session = await bb.sessions.create({
  proxies: true,
});

console.log("Session URL: https://browserbase.com/sessions/" + session.id);

Setting proxies: true makes a best-effort attempt to use a US-based proxy, falling back to a nearby country if none is available. When you need a specific place, pass a geolocation instead.

How do you set the proxy's location?

Pass a geolocation with a country, an optional state (within the US), and an optional city. If there is no proxy in the exact place you asked for, the closest available one is used. Browserbase's built-in proxies cover 201 countries.

import { Browserbase } from "@browserbasehq/sdk";

const bb = new Browserbase({ apiKey: process.env.BROWSERBASE_API_KEY! });

const session = await bb.sessions.create({
  proxies: [
    {
      type: "browserbase",
      geolocation: {
        city: "NEW_YORK",
        state: "NY",
        country: "US",
      },
    },
  ],
});

console.log("Session URL: https://browserbase.com/sessions/" + session.id);

You can also bring your own HTTP or HTTPS proxy with type: "external", or combine several proxies with domain-based routing rules so different sites route through different proxies. The proxies docs cover both.

Proxies and Verified: what's the difference?

A proxy controls the network identity your session presents, its IP address and apparent location. It does not, on its own, get an agent through the checks that protected sites run on automated traffic. That is what Verified is for. The two solve different halves of the same problem, and on protected sites they work best together.

What are the limits to know?

Browserbase's built-in residential proxies come from third-party providers, and those providers apply their own acceptable-use restrictions to certain high-risk site categories. Whether a given domain works through a built-in proxy depends on the provider routed for that session, which can change over time, so the reliable move is to test your target site directly rather than assume.

Categories that carry a higher risk of lower reliability include banking and financial services, most government domains, streaming and entertainment, ticketing, webmail providers, and gambling. If a session fails with a proxy error, treat that as the source of truth for that domain. Proxy usage is billed by total data transferred, with a 1 MB session minimum, and is available on the Developer plan and above.

If you're running automation from a server and seeing behavior you didn't see locally, add proxies: true to one session and compare. For location-specific work, set a geolocation and confirm the site renders the region you expect. The proxies docs cover geolocation, custom proxies, and routing rules in full.