Google Launches Google-Agent Identity Standard to Separate Legitimate AI Agents from Malicious Bots

Google added Google-Agent to its official list of web fetchers on March 20, 2026, creating a formal identity for AI systems running on Google infrastructure that browse websites on behalf of users. Project Mariner, Google’s experimental AI browsing tool from DeepMind, is the first product using it, according to Search Engine Journal.

Not a Crawler

Google-Agent is classified as a user-triggered fetcher, a category that includes tools like Google Read Aloud and NotebookLM. The distinction: a human initiated the request. Google’s position is that user-triggered fetchers “generally ignore robots.txt rules” because the fetch is a user’s proxy action, not autonomous crawling.

This is a deliberate departure from how competitors handle similar traffic. OpenAI’s ChatGPT-User and Anthropic’s Claude-User both function as user-triggered fetchers but respect robots.txt directives, Search Engine Journal reported. If a site blocks ChatGPT-User in robots.txt, ChatGPT will not fetch that page on a user’s behalf. Google made a different call: if a user asks Google-Agent to visit a page, it visits, regardless of robots.txt.

Website owners who relied on robots.txt as a universal access control mechanism now have a gap when it comes to Google-Agent traffic. Server-side authentication or access controls become the fallback.

Cryptographic Identity via Web Bot Auth

The more consequential development is Google-Agent’s experimental adoption of the Web Bot Auth protocol, an IETF draft standard that functions as a digital passport for bots. Each agent holds a private key, publishes its public key in a directory, and cryptographically signs every HTTP request. The receiving website verifies the signature and confirms, with cryptographic certainty, the visitor’s identity.

User agent strings can be spoofed. Cryptographic signatures cannot. Google is using the identity https://agent.bot.goog for the protocol, according to its developer documentation.

Akamai, Cloudflare, and Amazon (via AgentCore Browser) already support Web Bot Auth. Google’s adoption adds the critical mass the standard needs for broad deployment, per Search Engine Journal.

Three-Tier Visitor Model

Google-Agent effectively formalizes a three-tier visitor model for the web: human visitors browsing directly, crawlers indexing content for search and training (Googlebot, GPTBot, Google-Extended), and agents acting on behalf of specific humans in real time (Google-Agent, ChatGPT-User, Claude-User).

Each tier has different access rules, intentions, and expectations. A crawler indexes content. An agent completes a task: reading a product page, comparing prices, filling out a contact form, or booking an appointment.

The Infrastructure Pattern

The timing is notable. Within the past two weeks, Mastercard launched Know Your Agent tokenization for agent commerce, AWS released AgentCore Browser identity, and now Google has entered with Google-Agent and Web Bot Auth. The convergence signals that agent identity primitives are becoming table-stakes infrastructure before the agent economy can scale. Google is positioning itself to define the standard for how agents identify themselves on the open web, the same way it shaped mobile and cloud infrastructure standards in prior platform shifts.