---
title: "Headless browser"
url: https://proxy.wiki/glossary/headless-browser/
type: Glossary Term
author: "proxy.wiki editorial"
published: 2026-08-19
updated: 2026-08-19
site: proxy.wiki
topics: ["Proxy fundamentals"]
license: CC BY 4.0 — quote freely with attribution to https://proxy.wiki/
---

# Headless browser

> A real browser engine driven programmatically with no visible window. Powerful, slow and expensive in bandwidth.

**A headless browser is a full browser engine controlled by code instead of a person.** Chrome, Firefox and WebKit all support this mode, driven through tools such as Playwright, Puppeteer or Selenium.

## When it earns its cost

- Content rendered by JavaScript after page load.

- Flows requiring genuine interaction — clicks, scrolling, form entry.

- Targets whose [anti-bot systems](/glossary/anti-bot-system/) require a real client-side environment.

## What it costs

| Cost | Compared with an HTTP client |
| --- | --- |
| Memory and CPU | Substantially higher per worker |
| Latency | Full page load rather than one request |
| [Bandwidth](/glossary/bandwidth-billing/) | Often 10 to 50 times more, since every asset is fetched |

## The optimisation people miss

Block images, fonts, media and analytics at the request-interception layer. On a per-gigabyte plan this frequently cuts the bill by most of its value while leaving the rendered content intact.