Diffbot: what it is, what it does with your content, and what blocking it costs

What Diffbot is

Diffbot collects pages to train future models. It does not decide whether Diffbot can cite you in an answer today — that is a different crawler with a different token. Blocking Diffbot is a decision about your content being learned from, not about your visibility.

Operator: Diffbot
robots.txt token: Diffbot
User-agent on the wire: not published by the operator
Category: Model training

What blocking it actually costs

Diffbot builds a structured knowledge graph of the web that is sold to AI products; blocking it removes your entity from that graph.

How to block Diffbot

Add this to your robots.txt:

User-agent: Diffbot
Disallow: /

The token must appear on its own User-agent: line. A named group replaces the User-agent: * group rather than adding to it, so anything you also want disallowed for this crawler has to be repeated inside its group.

How to allow Diffbot

User-agent: Diffbot
Allow: /

An explicit allow is worth writing even when you have no blanket block: it documents the decision, and it survives someone later adding a restrictive User-agent: * rule without thinking about AI crawlers.

robots.txt is not the only thing that can block it

A permissive robots.txt does not mean Diffbot can reach you. WAF rules, Cloudflare's bot-management settings, rate limits and country blocks all sit in front of robots.txt and answer first. A site whose robots.txt welcomes Diffbot and whose edge returns 403 to it is blocked in every way that matters — and nothing in robots.txt will tell you so.

This is the gap the AI Crawler Access Checker was built to close: it reads robots.txt and sends a real request carrying the crawler's user-agent, so you see what the crawler sees.

Official documentation

Diffbot documents Diffbot at https://docs.diffbot.com/docs/en/guides-diffbot-crawler.