# What is a user agent (and how do AI agents identify themselves)?

> A user agent is the name a browser or bot sends with each web request. AI crawlers and agents use names like GPTBot, ChatGPT-User and Google-Agent.

_UK and US · Updated 2026-10-27 · Akkrev, https://akkrev.com/glossary/user-agent/_

A **user agent** is a short text string that every browser, crawler and bot sends with each request to a website, saying what it is. A Chrome browser on a Mac sends one string; Googlebot sends another; OpenAI's crawler sends one containing "GPTBot".

## How AI systems identify themselves

- **Training crawlers:** GPTBot, ClaudeBot, Google-Extended (a robots.txt token rather than a separate crawler).
- **Search crawlers:** OAI-SearchBot, Claude-SearchBot, PerplexityBot.
- **User-triggered fetchers:** ChatGPT-User, Claude-User, Perplexity-User, and [Google-Agent](https://akkrev.com/glossary/google-agent/) for agents on Google's infrastructure.

Some agentic browsers use an ordinary browser user agent and can't be told apart from people this way.

## Why it matters for hotels

User agents are what [robots.txt](https://akkrev.com/glossary/robots-txt/) rules and many [bot management](https://akkrev.com/glossary/bot-management/) settings act on. They're also easy to fake, which is why AI companies publish IP ranges and why signed requests such as [Web Bot Auth](https://akkrev.com/glossary/web-bot-auth/) are being adopted. Checking your server logs for these names shows which AI systems already visit your site.

## Why it matters for AI visibility

User agents tell you which AI crawlers and assistants are reading your site. That's an early signal of AI visibility.

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