What search engine does Claude use?
Brave Search, plus two other providers. Anthropic's subprocessor list (checked 24 October 2026) lists three companies for the purpose "Web Search":
| Subprocessor | Products listed | What it does (our summary of its site) |
|---|---|---|
| Brave Search | All products | A search engine with its own index |
| Parallel Web Systems | All except Claude for Government | Web search and extraction for AI agents |
| turbopuffer | All except Claude for Government | Vector and full-text search built on object storage |
The list doesn't say which company handles which part of a search, so the list alone can't tell you how a given answer was assembled. Claude's help page on using web search adds one more name: image results in Claude are powered by Bing.
Anthropic also runs its own search crawler, Claude-SearchBot, covered below. For a site owner, the useful reading is simple: Brave's index is the part you can check yourself, and Anthropic's crawler is the part you can allow or block.
How do we know Claude uses Brave?
Because Anthropic added Brave to that list when Claude's web search launched, and an independent test matched the results. Claude got web search on 20 March 2025, first for paid users in the US, according to Anthropic's launch post, which was updated on 27 May 2025 to say it was available on all plans worldwide.
A day after launch, programmer Simon Willison noted that the subprocessor list showed Brave Search added as of 19 March 2025. Willison asked Claude to "Search for pelican facts"; it searched for "Interesting pelican facts", and the ten results it cited matched that search on Brave exactly. The web_search tool definition Claude revealed had a parameters schema titled BraveSearchParams. TechCrunch reported the same finding on 21 March 2025 and noted that Brave also supplies search to Mistral's Le Chat.
Developers asked the same question about the API. In a May 2025 Hacker News thread on Anthropic's web search API, one commenter asked whether it was "using Brave under the hood, same as Claude's search feature". Anthropic's API documentation doesn't name a provider. In an August 2026 r/SEO thread, one commenter listed Brave as Claude's search engine. That matches the March 2025 evidence, but the current list names Parallel and turbopuffer too.
When does Claude search instead of answering from memory?
Claude searches when the answer depends on current or changing facts. Anthropic's web search tool documentation lists the triggers for the API version: recent events, current prices and statistics, information about specific organisations, people or products that might have changed, and explicit requests to search. It answers directly for stable knowledge, creative writing and content already in the chat.
That matters for B2B buyers. "What's the best CRM for a five-person agency?" may or may not trigger a search. "What does [your product] cost now?" is the kind of question the documentation says should. The help page adds two details:
- In the new Claude experience there is no web search toggle; Claude searches the web when it helps.
- You can make sure Claude searches by including "Search the web" or "Use web search" in the prompt.
Every answer that uses search includes citations, the help page says. So when you test, an answer with citations shows you which pages Claude read. An answer without them most likely came from the model itself.
Which crawlers decide whether Claude can see your site?
Four: Anthropic's three bots and Brave's crawler, which doesn't identify itself. Anthropic's crawler help page (dated 7 April 2026) describes three bots. Brave's crawler page describes the fourth:
| Crawler | What it does | If you block it |
|---|---|---|
| Claude-SearchBot | Analyses content to improve search results for Claude users | Anthropic says your content isn't indexed for search, which may reduce your visibility |
| Claude-User | Fetches pages when a user's question needs them | Claude can't retrieve your pages for that user |
| ClaudeBot | Collects content that could go into model training | Your future pages are excluded from training data |
| Brave's crawler | Builds Brave's index; uses no distinct user agent | You can't block it by name; it skips anything Googlebot can't crawl |
Two rules follow. Anthropic says blocking its IP addresses may not work reliably, because it stops its bots reading your robots.txt; use robots.txt instead. And Brave says if a page isn't crawlable by Googlebot, Brave's bot won't crawl it either, so a robots.txt that only blocks Googlebot from a folder keeps Brave's crawler out of it too.
One detail surprises people: Brave says robots.txt is not used to keep a page out of its index. To delist a page you use a noindex tag, and Brave has a form to request a re-fetch so it sees the change.
Which robots.txt rules should you use for Claude?
Pick the row that matches your goal. Each Anthropic bot is controlled separately in robots.txt, and Anthropic's crawler page says to add an opt-out to every subdomain you want it to cover.
| Your goal | ClaudeBot | Claude-SearchBot | Claude-User |
|---|---|---|---|
| Appear in Claude's answers, training allowed | Allow | Allow | Allow |
| Appear in Claude's answers, no training | Block | Allow | Allow |
| Keep Anthropic's bots off the site | Block | Block | Block |
If you want Claude to recommend you, pick the first or second row. The second row looks like this in robots.txt:
The third row has a limit worth knowing. Blocking Anthropic's bots doesn't take your pages out of Brave's index: Brave says robots.txt isn't used to prevent indexing, and delisting needs a noindex tag. Anthropic also supports the non-standard Crawl-delay rule if its crawling load is the worry, which is a gentler fix than a block.
How do you check whether Claude can find your site?
Test Brave directly, then test Claude, and compare. Brave says its results come solely from its own independent index, so a page missing from Brave can't come from that source. This takes about 15 minutes:
Check you are in Brave's index
Search site:yourdomain.com on Brave Search. The site operator is listed on Brave's search operators page. Note which key pages are missing: pricing, comparison and the main product page.
Run three buyer questions on Brave
For example: "best [category] for [buyer]", "[competitor] alternatives" and "[category] pricing". Write down the top 10 URLs for each.
Ask Claude the same questions
Start each with "Search the web:" so a search runs, and log every cited URL. Where the citations overlap your Brave list, Brave's ranking is your lever.
Check your logs and robots.txt
Look for Claude-SearchBot and Claude-User in your server logs, and confirm robots.txt doesn't disallow them or Googlebot on the pages that matter.
Repeat the Claude step on another day before you draw conclusions; AI answers change from run to run. If Claude does send visitors, our guide to tracking ChatGPT, Perplexity and Claude traffic in GA4 shows how to count them.
What does this mean for a small site?
It means your Google ranking is not your Claude ranking. Brave builds a separate index, and the pages Claude cites depend at least partly on what that index returns for Claude's own queries. Ahrefs' 15,000-prompt overlap study (updated May 2026) found that only 12% of URLs cited by ChatGPT, Gemini and Copilot ranked in Google's top 10 for the same prompt. That study didn't include Claude, so treat it as a warning, not a Claude number.
Three things are worth doing for a site with little authority:
- Remove access problems first. One commenter's sample suggests they are rare, but a block is total. In the r/SEO thread, a commenter who audits small-business sites said that in a sample of 3,111 law firm sites, exactly one blocked AI crawlers. Check you aren't that one.
- Win the pages Brave already ranks. If your Brave results for buyer questions are roundups and comparison posts, get listed on those. Our audit for when ChatGPT recommends your competitor covers the outreach and the homepage fixes, and most of it applies to Claude.
- Say who you are for in one sentence. Put a line such as "[Product] is the [category] for [buyer] who [job]" on your homepage and pricing page, so a Brave result for "best [category] for [buyer]" has your own words to match.
None of this needs a separate "Claude strategy". Our look at whether GEO is just SEO sorts what is new from what is recycled. To watch competitors' visibility in AI assistants without running prompts by hand, Siela's Competitor Watch checks it alongside their rankings, ads and launches, in a briefing every Monday morning.
Frequently asked questions
Does Claude use Google search?
Anthropic doesn't list Google among its web search subprocessors. Its subprocessor list, checked on 24 October 2026, names Brave Search, Parallel Web Systems and turbopuffer for web search. Claude's help page says image results are powered by Bing. Brave's crawler follows Googlebot's access rules on your site, so robots.txt rules for Googlebot still matter for Claude.
Can I submit my site to Brave Search?
Brave's crawler help page describes a form to request a re-fetch of a page, which it mentions for delisting with a noindex tag, and a form for reporting pages that no longer exist. The page doesn't describe a webmaster console or sitemap submission. The practical route is to make sure Googlebot can crawl your pages, because Brave won't crawl what Googlebot can't.
Should I block ClaudeBot if I want to appear in Claude's answers?
Blocking ClaudeBot only affects training: Anthropic says it signals that your future pages should be excluded from training data. Search visibility depends on Claude-SearchBot, which indexes content for search, and Claude-User, which fetches pages when a user asks. Anthropic says disabling either may reduce your visibility, so allow those two even if you block ClaudeBot.
How do I make Claude search the web instead of answering from memory?
Include "Search the web" or "Use web search" in your prompt, as Claude's help page suggests. In the new Claude experience there is no toggle; Claude decides when to search. Anthropic's documentation says it searches for current or changing facts, such as prices or information about organisations and products, and answers directly for stable knowledge.
How much does Claude's web search cost developers?
Anthropic's documentation lists web search on the Claude API at $10 per 1,000 searches, plus standard token costs for the search results Claude reads (checked 24 October 2026). Developers can limit searches per request with max_uses and restrict results with allowed or blocked domain lists. Citations are always included in the response.
Sources
- Anthropic Trust Center: Subprocessors (checked 24 Oct 2026)
- Simon Willison: Anthropic Trust Center: Brave Search added as a subprocessor (21 Mar 2025)
- TechCrunch: Anthropic appears to be using Brave to power web search for its Claude chatbot (21 Mar 2025)
- Anthropic: Claude can now search the web (20 Mar 2025, updated 27 May 2025)
- Claude Help Center: Enable and use web search (checked 24 Oct 2026)
- Claude API docs: Web search tool (checked 24 Oct 2026)
- Claude Help Center: Does Anthropic crawl data from the web, and how can site owners block the crawler? (7 Apr 2026)
- Brave Search Help: Brave Search Crawler (checked 24 Oct 2026)
- Brave Search Help: Brave Search Index and the Right to be Forgotten (checked 24 Oct 2026)
- Brave Search Help: Search Operators (checked 24 Oct 2026)
- Hacker News: Web search on the Anthropic API (7 May 2025)
- r/SEO: How do you get your site recommended by ChatGPT and Claude? (5 Aug 2026, checked 24 Oct 2026)
- Ahrefs: Only 12% of AI Cited URLs Rank in Google's Top 10 for the Original Prompt (11 Aug 2025, updated 31 May 2026)
- Parallel Web Systems homepage (checked 24 Oct 2026)
- turbopuffer homepage (checked 24 Oct 2026)