Claude in Chrome

What it is

Claude in Chrome is an extension for Google's Chrome browser. It lets Claude see the pages a user has open, click buttons, and fill in forms on the user's behalf. Because the work happens inside the user's own browser, the extension can act on sites that the user is already signed in to, which is also why its safety design drew close attention from the start.

Origins

Anthropic piloted Claude in Chrome from 25 August 2025. The pilot was limited to 1,000 Max plan users, selected from a waitlist.^[1]

Anthropic published test results on prompt injection, an attack in which text on a web page tries to make the AI follow instructions that the user never gave. In 123 adversarial test cases across 29 attack scenarios, such attacks succeeded 23.6% of the time without safeguards and 11.2% of the time with the new mitigations. On four browser-specific attack types, the rate fell from 35.7% to 0%.^[1]

Waitlisted Max users gained access with Claude Sonnet 4.5 in September 2025.^[2]

On 24 November 2025 the extension opened in beta to all Max subscribers, adding scheduled tasks and multi-tab workflows. On 18 December 2025 it expanded to Pro, Team and Enterprise plans, with a Claude Code integration and administrator allowlists and blocklists for sites.^[1]

Safety and control

The prompt-injection results are the most detailed public figures on the extension, and they show why the extension is designed around controls. An attack that works through a web page is different from a normal chat attack, because the page content itself is the source of the instructions. The 23.6% and 11.2% figures describe Anthropic's own test set, so they are measures of that set rather than guarantees for every page on the web. The reduction on browser-specific attacks, from 35.7% to 0%, is the most striking number in the test results, though it is also drawn from the same set of cases.^[1]

Administrator allowlists and blocklists let an organisation decide which sites the extension may use or must avoid. Those controls matter for teams that want Claude to work in a browser without giving it free access to every site.^[1]

Where it stands

Wikipedia reports that Claude in Chrome became generally available in August 2026.^[3] That makes it one of the browser-based agents in the Claude family, alongside the coding and knowledge-work agents that also act on a user's behalf.

The extension is an example of an agent working in a place people already use. It shows Claude acting as a participant in a web session rather than only producing text about one, which is why the question of how its actions are limited is central to its design.^[1][2]