---
description: Detect and block requests with invalid headers.
title: Browser Integrity
image: https://developers.cloudflare.com/og-docs.png
---

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# Browser Integrity

Last updated Aug 24, 2026|Copy as Markdown|[View as Markdown](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/learning-paths/application-security/default-traffic-security/browser-integrity/index.md)|[Agent setup](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/agent-setup/)

Cloudflare's Browser Integrity Check (BIC) looks for common HTTP headers abused most commonly by spammers and denies access to your page.

It also challenges visitors without a user agent or with a non-standard user agent such as commonly used by abusive bots, crawlers, or visitors.

[BIC is enabled by default](https://docs-durable-objects-instance-replaced-errors.previews.developers.cloudflare.com/waf/tools/browser-integrity-check/).

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