Findings · 2026-10-08 · By VSNARY | Emmanuel Orta · 0 views
Who signs their agent requests? Web Bot Auth in October 2026
User agents can be typed by anyone and IP ranges do not fit agents that run in shared browsers. Signed requests do. Which operators document signing today, the identity each one signs as, and which large operators still rely on address ranges.
As of 8 October 2026, operators documenting Web Bot Auth signatures include OpenAI (ChatGPT’s cloud browser signs as https://chatgpt.com), Google (experimenting with https://agent.bot.goog for Google-Agent), Cloudflare (Browser Rendering) and the first signed-agent cohort Cloudflare announced in August 2025: ChatGPT agent, Block’s Goose, Browserbase and Anchor Browser. Anthropic and Perplexity document published IP ranges for their crawlers and fetchers but no request signing.
A user agent is a claim anyone can type: on this site 86% of Perplexity-User claims were forged. Address ranges fix that for crawlers, which run from their operator’s own machines. They fit agents badly, because an agent working for a person often runs in a shared cloud browser whose addresses also serve other customers. Web Bot Auth is the answer the industry is converging on: the agent signs each request, names the domain that holds its keys, and the site checks the signature against those keys.
Who documents signing today #
Each row below comes from the operator’s own documentation or announcement, read on 8 October 2026.
| Operator | Agent | Signs as | Source |
|---|---|---|---|
| OpenAI | ChatGPT’s cloud browser (ChatGPT Work) | https://chatgpt.com; keys at chatgpt.com/.well-known/http-message-signatures-directory | OpenAI Help Center, agent allowlisting |
| Google-Agent | Experimenting with https://agent.bot.goog; also publishes user-triggered-agents.json ranges | Google crawler documentation | |
| Cloudflare | Browser Rendering | Signed since Web Bot Auth launched | Cloudflare, “The age of agents”, 28 Aug 2025 |
| Block, Browserbase, Anchor Browser | Goose, and two remote-browser platforms | First cohort of Cloudflare’s signed-agent category, with ChatGPT agent | Same announcement |
| CrawlCheck | Our own crawler | Every request signed; directory at /.well-known/http-message-signatures-directory | This site |
Who documents ranges instead #
| Operator | What it documents | Signing documented? |
|---|---|---|
| Anthropic | ClaudeBot, Claude-User and Claude-SearchBot by user agent; ranges at claude.com/crawling/bots.json | No |
| Perplexity | PerplexityBot and Perplexity-User by user agent; ranges at perplexity.com/perplexitybot.json and perplexity-user.json | No |
Neither is a weakness for the crawlers, which run from those ranges and verify cleanly: ClaudeBot and PerplexityBot are forged in under 2% of claims here. It matters for agents. As assistants move from fetching a page to operating a browser for a person, a range file stops describing where the traffic comes from, and a signature is the only identity that travels with the request.
What a signature proves, and what it does not #
- It proves the request came from whoever holds the private key published in the named directory, within the signature’s time window.
- It does not prove what the agent will do with the page, whether it will respect your robots.txt, or that the person behind it is who they say.
- It replaces the user agent as the thing to allow or block on, for operators that sign.
If you allow a signed agent, allow it by the identity in Signature-Agent after verifying the signature, never by the user agent string next to it. The Web Bot Auth guide shows the verification step by step.
Method #
Operators were included only where their own documentation or announcement states that they sign, and with the identity they state. Anthropic’s and Perplexity’s crawler pages were read for any mention of Web Bot Auth, HTTP message signatures or Signature-Agent and contain none. This table will be re-read and dated when an operator changes its documentation.
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Questions this post answers
Which AI agents use Web Bot Auth?
As of 8 October 2026: ChatGPT’s cloud browser (signs as https://chatgpt.com), Google-Agent (Google is experimenting with https://agent.bot.goog), Cloudflare Browser Rendering, and the agents in Cloudflare’s first signed-agent cohort: ChatGPT agent, Block’s Goose, Browserbase and Anchor Browser.
Does Claude or Perplexity sign its requests?
Not according to their documentation as read on 8 October 2026. Anthropic and Perplexity identify their crawlers and fetchers by user agent and publish IP ranges (claude.com/crawling/bots.json; perplexity.com/perplexitybot.json and perplexity-user.json).
What does a Web Bot Auth signature prove?
That the request came from whoever holds the private key published in the directory named by the Signature-Agent header, within the signature’s validity window. It does not prove how the agent will behave.
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