Explainer
How Claude web search works: what is confirmed and what is not
How Claude web search works: Anthropic documents what the tool does, but never names the search engine behind it. The evidence points to Brave. It is a data processor added one day before launch, a leaked parameter name, and matched search results. Anthropic has not confirmed any of it. Here is what is documented, what is only inferred, and what to do.
Key takeaways
- Anthropic's web search docs describe the tool functionally and name no search provider anywhere.[1]
- The evidence for Brave is strong but unconfirmed: a subprocessor added one day before launch, a leaked BraveSearchParams field, and matched citations.[4]
- Anthropic documents three crawlers: ClaudeBot for training, Claude-User for live requests, and Claude-SearchBot for search quality.[3]
In this article
What does Anthropic document?#
Not much. Claude's web search tool gives it direct access to current web content, so it can answer beyond its training cutoff, and the response includes citations drawn from the search results.[1] Claude decides when to search, the API runs the searches and hands Claude the results, and Claude answers with cited sources.[1] The tool launched on the Anthropic API on May 7, 2025, for Claude 3.7 Sonnet, the upgraded Claude 3.5 Sonnet, and Claude 3.5 Haiku, at $10 per 1,000 searches plus standard token costs.[2]
What does Anthropic not say?#
Nowhere in Anthropic's web search documentation or launch post is a search provider named.[1] Perplexity publishes its index scale. OpenAI names Bing and Shopify. For a tool whose job is to fetch and cite the live web, the engine underneath is the key fact, and it is the one Anthropic leaves out. Compare with how Perplexity search works and how ChatGPT search works.
Does Claude web search use Brave?#
Probably, but it is not confirmed. Three threads, reported by developer Simon Willison and echoed in the tech press, point to Brave Search.[4][8]
| Evidence | What was found | Strength |
|---|---|---|
| Legal disclosure | Brave Search added to Anthropic's list of data processors on March 19, 2025, one day before web search launched in the Claude app | Anthropic's own record |
| Tool schema | A parameter named BraveSearchParams in the schema Claude uses to call tools | Observed, not stated by Anthropic |
| Matching results | The same query in Claude and in Brave returned matching citations | Reproducible |
| Confirmation | None on the record from Anthropic | Missing |
Brave sells access to what it calls a fully independent web index of over 30 billion pages.[5][6]Even the person who built the case hedges with the word “presumably.”[4] So the evidence points to Brave, and Anthropic has never confirmed it.
Does Anthropic run its own crawlers?#
| Crawler | What Anthropic says it does |
|---|---|
| ClaudeBot | Collects web content that could contribute to training |
| Claude-User | Fetches pages for live user requests |
| Claude-SearchBot | Navigates the web to improve search result quality |
So Anthropic runs some of its own search crawling, while the live tool appears to lean on an outside provider. Anthropic documents the two separately and does not explain how they relate. One more detail: on Claude.ai, image search is stated to be powered by Bing.[7]
What should you do about it?#
Allow Claude-User and Claude-SearchBot
Claude-User retrieves your content for a live query, and Claude-SearchBot works on search quality.[3] Blocking them removes you from the paths Claude uses to answer with your page. ClaudeBot is a separate training decision.
Check your Brave presence
If Claude's web search reads Brave's index,[4] being present in an index of over 30 billion pages[6] is a step few people take. It is a bet based on evidence, not a guarantee.
Measure the outcome
Since Anthropic will not confirm what powers the search, ask Claude the questions your buyers ask, several times, and watch whether it cites you.
For the full checklist, see how to get a SaaS company into Claude answers. Noetio's AI SEO services measure this on ChatGPT, Perplexity, Gemini and Google, find the cause, and check again after the fix.
FAQ
- What search engine does Claude use?
- Anthropic does not say. Its documentation names no provider. Anthropic's data processor list added Brave Search the day before launch, and a Claude tool schema had a BraveSearchParams field, so the evidence points to Brave. Anthropic has not confirmed it.
- Does Claude have its own web crawler?
- Yes. Anthropic documents three: ClaudeBot for training, Claude-User for live user requests, and Claude-SearchBot for improving search result quality.
- How much does Claude web search cost on the API?
- At launch on May 7, 2025, Anthropic priced it at $10 per 1,000 searches plus standard token costs.
- How do I get Claude to cite my site?
- Allow Claude-User and Claude-SearchBot, make sure your page is in the index Claude reads, and check the results by asking Claude your buyers' questions several times. Anthropic publishes no ranking rules.
Not cited by Claude? See why, and what fixes it.
Sources
- The web search tool gives Claude “direct access to real-time web content”; the API “runs the searches and provides Claude with the results”; no provider is named: Anthropic, “Web search tool” documentation.
- Web search launched on the Anthropic API on May 7, 2025 at “$10 per 1,000 searches plus standard token costs”: Anthropic, “Web search on the Anthropic API”, May 7, 2025.
- Three crawlers: ClaudeBot (training), Claude-User (live requests), and Claude-SearchBot, which “navigates the web to improve search result quality”: Anthropic Support, “Does Anthropic crawl data from the web?”.
- Brave Search added to Anthropic's subprocessor list on March 19, 2025 (a day before launch); a BraveSearchParams field in Claude's tool schema; Claude's citations matching Brave's results; no confirmation on the record from Anthropic: Simon Willison, “Anthropic's new subprocessor: Brave Search”, March 21, 2025.
- Brave Search API is “powered by Brave Search, a completely independent index of the Web”: Brave, “Brave Search API”.
- Brave's “independent index of over 30 billion pages”: Brave, “What sets the Brave Search API apart”.
- On Claude.ai, image search is “powered by Bing”: Anthropic Support, “Enabling and using web search”.
- Corroborating coverage that Anthropic appears to use Brave for Claude's web search, with no confirmation on the record from Anthropic: TechCrunch, March 21, 2025.
Claims about what Anthropic documents quote Anthropic's own docs, blog, and support pages, retrieved and verified on July 22, 2026. The Brave dependency is reported as evidenced, not confirmed. It rests on Anthropic's own subprocessor disclosure plus independent, reproducible testing. Brave's index figures come from Brave's own pages.
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