# What is a headless browser?

> A headless browser runs web pages without a visible window, controlled by software. AI agents and testing tools use them to open and operate websites.

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

A **headless browser** is a real web browser, such as Chromium, running without a visible window and controlled by code. It loads pages, runs their scripts, clicks and types, exactly like a normal browser, but a program is driving it.

## Who uses them

- **AI agents** that browse on a user's behalf often run headless browsers in the cloud.
- **Testing tools** use them to check websites automatically. Our Agent Booking Index pilot used a scripted cloud browser.
- **Scrapers** use them too, which is why security services watch for them.

## Why hotel sites sometimes block them

[Bot management](https://akkrev.com/glossary/bot-management/) tools look for signs of headless browsers and may challenge or block them. That stops scrapers, but can also stop a guest's agent. Signed requests from known agents, such as [Web Bot Auth](https://akkrev.com/glossary/web-bot-auth/), give security tools a better way to tell them apart.

## Why it matters for AI visibility

Headless browsers are how many crawlers and agents read sites. Pages that only render with heavy scripts can be harder for them.

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