---
title: "Caddy: block by user-agent — AI Crawler Index"
description: "A Caddy matcher plus respond directive. Caddy's header_regexp matcher is case-sensitive, so the pattern is written with an inline (?i) flag."
canonical: "https://www.pathwren.workers.dev/snippet/caddy.html"
url: "https://www.pathwren.workers.dev/snippet/caddy.md"
format: "markdown"
source: "the bytes of /snippet/caddy.html, in the build that wrote the page"
generator: "surfaces/ai-crawler-index/build.py"
generated: "2026-09-03T07:55:35+00:00"
license: "CC0-1.0"
---

# Caddy: block by user-agent

> A Caddy matcher plus respond directive. Caddy's header_regexp matcher is case-sensitive, so the pattern is written with an inline (?i) flag.

A Caddy matcher plus respond directive. Caddy's header_regexp matcher is case-sensitive, so the pattern is written with an inline (?i) flag.

```bash
curl -s https://www.pathwren.workers.dev/snippet/caddy.txt -o Caddyfile
```

```text
# AI Crawler Index — Caddy
# curl -s https://www.pathwren.workers.dev/snippet/caddy.txt
@ai_training header_regexp User-Agent "(?i)(GPTBot|ClaudeBot|anthropic\-ai|GoogleOther|Bytespider|TikTokSpider|meta\-externalagent|FacebookBot|cohere\-training\-data\-crawler|Webzio\-Extended|SemrushBot\-OCOB|GoogleOther\-Image|GoogleOther\-Video|YandexAdditional|YandexAdditionalBot|SBIntuitionsBot|ICC\-Crawler|Cotoyogi|ISSCyberRiskCrawler|Sidetrade\ indexer\ bot|QuillBot|Factset_spyderbot|Poseidon\ Research\ Crawler|Reflectionbot|Linguee\ Bot)"
@disputed    header_regexp User-Agent "(?i)(Bytespider|TikTokSpider|ISSCyberRiskCrawler|Thinkbot|Linguee\ Bot)"

handle @disputed {
	respond "403 - see /robots.txt" 403
}
handle @ai_training {
	header X-Crawler-Class "ai-training"
	# file_server / reverse_proxy as usual
}
```

[raw](https://www.pathwren.workers.dev/snippet/caddy.txt) · [json](https://www.pathwren.workers.dev/snippet/caddy.json)

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## Machine copies of this page

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- [Markdown](https://www.pathwren.workers.dev/snippet/caddy.md) — this document

This document is a markdown rendering of [https://www.pathwren.workers.dev/snippet/caddy.html](https://www.pathwren.workers.dev/snippet/caddy.html), generated from that page's own bytes in the same build. The HTML page is canonical.