In short. Google-GeminiNotebook retrieves user-provided notebook sources, while Google-NotebookLM is the former agent supported until August 2026.

Definition: As of October 2026, Google notebook fetchers are user-triggered clients that retrieve individual web addresses supplied as project sources in Gemini Notebook. Google documents Google-GeminiNotebook as their current request identifier and Google-NotebookLM as the former agent, supported until August 2026.

Key facts

Google's user-triggered fetcher list gives both mobile and desktop request strings containing Google-GeminiNotebook.
Google's crawler overview describes fetchers as programs that typically make a single request on a user's behalf.
Google's request verification guide provides checks using domain-name lookups or published IP address ranges.

Which identifiers appear in requests?

A user agent is an identifier supplied in the HTTP User-Agent request header. Google's Gemini Notebook listing supplies this desktop string:

Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/137.0.0.0 Safari/537.36 (compatible; Google-GeminiNotebook; +https://developers.google.com/crawling/docs/crawlers-fetchers/google-gemininotebook)

The same listing places Google-NotebookLM under “Former agent (supported until August 2026).” Log reports that group notebook traffic can therefore distinguish the current identifier from the former one. The mobile string also contains Google-GeminiNotebook, allowing reports to group both documented variants by that identifier.

What triggers a fetch, and how does robots.txt apply?

Google's fetcher documentation associates the notebook agent with individual URLs that users provide as sources for their projects. It describes user-triggered fetchers as generally ignoring robots.txt, the file that expresses crawler access rules, because a user requests the fetch.

Google's overview of crawling clients classifies Googlebot among common crawlers, which always respect robots.txt rules for automatic crawls. For a website owner, this distinction makes the initiating product relevant when interpreting access logs or reviewing a robots.txt policy. The notebook identifier describes a source-retrieval request associated with the notebook product.

How can a website verify a request?

Google's verification guide describes a manual procedure using DNS, the domain name system. A reverse DNS lookup starts with the requesting IP address and returns a hostname. The returned hostname must belong to googlebot.com, google.com or googleusercontent.com. A forward lookup then resolves that hostname back to an IP address, which must match the original address in the server log.

For Google-controlled fetchers, the guide associates addresses in user-triggered-fetchers-google.json with google.com hostnames. It lists the hostname pattern google-proxy-***-***-***-***.google.com. For automated verification, the guide describes matching request addresses against Google's published IP ranges, represented in CIDR notation, a format for address blocks.

FAQ

Which identifier should I look for in current logs?

Google's notebook fetcher listing names Google-GeminiNotebook in both request variants. It identifies Google-NotebookLM as the former agent, with support until August 2026.

Can I authenticate a request from its user-agent string alone?

Google's verification guide recommends checking the requesting IP address through DNS lookups or published IP ranges. You can use these checks when evaluating a request that claims a Google identity.

Sources

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