What is an agentic browser?

By Nik Andreev, Founder & SEO specialist · Last reviewed · Editorial policy

An agentic browser is a real web browser driven by an AI agent that browses sites on a person's behalf: it loads pages, runs JavaScript, clicks and fills in forms. Because it uses a normal browser, it can look like a human visitor. Some, like ChatGPT agent's cloud browser, prove their identity with Web Bot Auth signatures.

Full guide How to detect AI agents like ChatGPT agent on your website The verification ladder that tells signed, declared and hidden agents apart. Read the guide →

At a glance

Type
AI agent operating a real browser for a user
Examples
ChatGPT agent (OpenAI cloud browser), Google-Agent, Anthropic-hosted browsers (Claude-Agent)
Runs JavaScript
Yes, so it can appear in client-side analytics as a person
How it identifies itself
Varies: a Web Bot Auth signature, a user-agent token, or nothing
How to verify
Verify the signature (RFC 9421) or match the source IP to the operator's list
Standard
Web Bot Auth, built on HTTP Message Signatures (RFC 9421). Still an IETF draft

How to spot it

  • Signed: look for Signature, Signature-Input and Signature-Agent headers. ChatGPT agent sends Signature-Agent: "https://chatgpt.com"; some Google-Agent requests send https://agent.bot.goog. Verify the signature against the operator’s published keys.
  • Declared: a normal browser user agent plus a token such as Claude-Agent or Google-Agent. Confirm the source IP is on that operator’s list (for Claude-Agent, claude.com/.well-known/sail).
  • Hidden: some agentic browsers send no marker at all. They can only be told apart by behavior, so keep the full request headers in your server logs.

Related terms

Signed agent An agent whose requests carry a verifiable cryptographic signature. Headless browser A browser driven by code with no visible window. Common for scripts and scrapers. ChatGPT-User OpenAI's simple fetcher for user requests. It does not run a full browser.

Quick answers

Is an agentic browser a crawler?

No. A crawler fetches pages on its own schedule. An agentic browser acts for one person in real time, often on pages that need interaction.

Can I tell an agentic browser from its user agent?

Not always. Some add a token such as Claude-Agent or Google-Agent. ChatGPT agent's browser can look like ordinary Chrome, so its signature is the reliable signal.

Does every Google-Agent request carry a signature?

No. Google says its Web Bot Auth support is experimental and it does not sign every request. Fall back to an IP check.

Sources