How Googlebot crawls the web

In this episode of Search Off the Record, Martin and Gary from the Google Search Relations team take a deep dive into how Googlebot and web crawling work—past, present, and future. Through their humorous and thoughtful conversation, they explore how crawling evolved from the early days of the internet, when scripts could index a chunk of the web from a single homepage, to the more complex and considerate systems used today. They discuss the basics of what a crawler is, how tools like cURL or Wget relate, and how policies like robots.txt ensure crawlers play nice with web infrastructure.

The conversation also covers Google's internal shift to unified infrastructure for all crawling needs, highlighting how different teams moved from separate crawlers to a shared system that enforces consistent policies. They explain why some fetches bypass robots.txt (like user-initiated actions) and the rising impact of automated traffic from new products and AI agents. With a nod to initiatives like Common Crawl, the episode ends with a look at the road ahead, acknowledging growing internet congestion but remaining optimistic about the web's capacity to adapt.

Resources:

Episode transcript → https://goo.gle/sotr092-transcript

Chapters:

Chapters: 0:00 - Intro 0:53 - What is a Web Crawler? 3:11 - Building a Minimal Crawler 6:12 - Ethical Crawling: Robots.txt & Host Health 7:42 - BackRub and Early Crawling Challenges 11:02 - The Anatomy of a Search Engine Paper 13:09 - Crawling Across Google Products 16:51 - New Crawlers & User Agent Strings 22:38 - Crawlers Beyond Google 23:17 - The Evolution of Crawlers 26:32 - Bad Actors and Overpowering Servers 27:31 - Reducing the Footprint on the Internet 28:44 - The Future of Crawlers 31:29- Conclusion

Listen to more Search Off the Record → https://goo.gle/sotr-yt

Subscribe to Google Search Channel → https://goo.gle/SearchCentral

Search Off the Record is a podcast series that takes you behind the scenes of Google Search with the Search Relations team.

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Speakers: Martin Splitt, Gary Illyes

Products Mentioned: Googlebot, Search