Anthropic’s new AI search feature digs through the web for answers

On Thursday, Anthropic introduced web search capabilities for its AI assistant Claude, enabling the assistant to access current information online. Previously, the latest AI model that powers Claude could only rely on data absorbed during its neural network training process, having a "knowledge cutoff" of October 2024.

Claude's web search is currently available in feature preview for paid users in the United States, with plans to expand to free users and additional countries in the future. After users enable the feature in their profile settings, Claude will automatically determine when to use web search to answer a query or find more recent information.

The new feature works with Claude 3.7 Sonnet and requires a paid subscription. The addition brings Claude in line with competitors like Microsoft Copilot and ChatGPT, which already offer similar functionality. ChatGPT first added the ability to grab web search results as a plugin in March 2023, so this new feature is a long time coming.

A Claude AI web search demonstration video from Anthropic.

"This was sorely needed," wrote independent AI researcher Simon Willison on his blog. "ChatGPT, Gemini and Grok all had this ability already, and despite Anthropic's excellent model quality it was one of the big remaining reasons to keep other models in daily rotation."

Interestingly, the web search feature seems somewhat "agentic" in the sense that it can autonomously loop through several attempts at searching the web to drill down for an answer—you might call it a very simplified version of the "Deep Research" agent trend that recently came to Google Gemini and ChatGPT.

A screenshot example of what Anthropic Claude's web search process looks like, captured March 21, 2025. Credit: Benj Edwards

Anthropic positions the web search feature as potentially good for various use cases, including for "sales teams" doing account planning, "financial analysts" assessing market data, "researchers" building grant proposals, and "shoppers" comparing prices and features of products.

Anthropic's blog mentions, "Sales teams can transform account planning and drive higher win rates through informed conversations with prospects by analyzing industry trends to learn key initiatives and pain points," which sounds like Claude may have had a hand in writing about itself.

Caution over citations and sources

Claude users should be warned that large language models (LLMs) like those that power Claude are notorious for sneaking in plausible-sounding confabulated sources. A recent survey of citation accuracy by LLM-based web search assistants showed a 60 percent error rate. That particular study did not include Anthropic's new search feature because it took place before this current release.

When using web search, Claude provides citations for information it includes from online sources, ostensibly helping users verify facts. From our informal and unscientific testing, Claude's search results appeared fairly accurate and detailed at a glance, but that is no guarantee of overall accuracy. Anthropic did not release any search accuracy benchmarks, so independent researchers will likely examine that over time.

A screenshot example of what Anthropic Claude's web search citations look like, captured March 21, 2025. Credit: Benj Edwards

Even if Claude search were, say, 99 percent accurate (a number we are making up as an illustration), the 1 percent chance it is wrong may come back to haunt you later if you trust it blindly. Before accepting any source of information delivered by Claude (or any AI assistant) for any meaningful purpose, vet it very carefully using multiple independent non-AI sources.

A partnership with Brave under the hood

Behind the scenes, it looks like Anthropic partnered with Brave Search to power the search feature, from a company, Brave Software, perhaps best known for its web browser app. Brave Search markets itself as a "private search engine," which feels in line with how Anthropic likes to market itself as an ethical alternative to Big Tech products.

Simon Willison discovered the connection between Anthropic and Brave through Anthropic's subprocessor list (a list of third-party services that Anthropic uses for data processing), which added Brave Search on March 19.

He further demonstrated the connection on his blog by asking Claude to search for pelican facts. He wrote, "It ran a search for 'Interesting pelican facts' and the ten results it showed as citations were an exact match for that search on Brave." He also found evidence in Claude's own outputs, which referenced "BraveSearchParams" properties.

The Brave engine under the hood has implications for individuals, organizations, or companies that might want to block Claude from accessing their sites since, presumably, Brave's web crawler is doing the web indexing. Anthropic did not mention how sites or companies could opt out of the feature. We have reached out to Anthropic for clarification.

Caution over citations and sources

A partnership with Brave under the hood

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