Blocking LLMs from proprietary data?

Summary

Voices of Search Podcast

Episode: Blocking LLMs from Proprietary Data?
Date: April 2, 2026
Host: Tyson
Guest: Kaspar Siminsky, Senior Director at Search Brothers & former Google Search Team

Episode Overview

In this concise episode, Tyson and Kaspar Siminsky discuss the challenges and realities of keeping proprietary data away from Large Language Models (LLMs) and crawlers, especially for enterprise-level organizations. The conversation addresses the binary nature of web visibility and offers practical advice for those concerned about sensitive or proprietary content.

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Key Discussion Points & Insights

The Binary Nature of Web Accessibility

• Defining Proprietary Data
  Kaspar opens by questioning how proprietary the data is:

  • If it's truly sensitive or critical, it arguably shouldn't be available on the public web at all.

• Visibility Equals Crawlability

  • "If it's public, if it's accessible, it's going to get crawled." — Kaspar Siminsky (02:25)
  • The web operates on a clear binary: content is either available to all, including bots and LLMs, or it's entirely restricted.

• The Inevitability of Leaks

  • Even with various crawling restrictions, there's always a risk:
    • "If it's crawled by some bots, chances are it's going to leak." — Kaspar Siminsky (02:25)

Practical Approach for Enterprises

• Protecting Truly Proprietary Data

  • The most effective approach: don’t put sensitive content online if you want to guarantee it stays off LLMs and away from crawlers.

• Limits of Technical Barriers

  • Robots.txt, CAPTCHAs, and other barriers can help, but they aren't foolproof against determined actors or evolving crawling strategies.

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Notable Quotes & Memorable Moments

• On the Hypothetical of Blocking LLMs:

  • "If it's really proprietary and if it's something that we do not want to get scraped and crawled, ultimately then it shouldn't be accessible in the first place."
    — Kaspar Siminsky (00:41)

• On Public Content Risks:

  • "If it's public, if it's accessible, it's going to get crawled. Ultimately, it's kind of like a binary choice."
    — Kaspar Siminsky (02:25)

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Important Segment Timestamps

• 00:22: Episode premise; introduction of guest Kaspar Siminsky—expert credentials and introduction of the topic.
• 00:41: Discussion begins on what it means to block LLMs from proprietary data.
• 02:25: Kaspar outlines the binary nature of online content and the risk of exposure if made public.

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Tone & Takeaway

The conversation is frank and practical—Kaspar avoids technical jargon and opts for real-world logic: Unless you're willing to keep your proprietary data offline, you must assume that it could eventually be accessed by LLMs and crawlers. For enterprises especially, this means rethinking which assets are truly suitable for online exposure.

Bottom line: If you don't want it scraped, don’t let it be visible online—no technical fix is foolproof.

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Summary At-a-Glance

• If it's on the web, it may be accessed by LLMs/crawlers—there’s no middle ground.
• Protect truly sensitive information by keeping it offline.
• Technical solutions offer only limited protection; the best defense is not publishing.
• Enterprise decision-makers must make careful, binary choices about data exposure.

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For more information about Kaspar Siminsky, visit Search Brothers or check the show notes for his LinkedIn profile.

Transcript

[Tyson]

The Voices of Search Podcast is a proud member of the I Hear Everything Podcast network. Looking to launch or scale your podcast, I Hear Everything delivers podcast production, growth and monetization solutions that transform your words into profit. Ready to give your brand a voice? Then visit iheareverything.com My name is Tyson

and joining me today is Kaspar Siminsky, Senior Director at Search Brothers and former member of Google Search Team. Today, Casper and I are going to be talking about the latest changes in the industry and how you can take that into practice, especially in the enterprise arena. What are your thoughts on blocking LLMs from proprietary data?

[Kaspar Siminsky]

Well, it really depends, right? How proprietary is the data? I mean, if it's really proprietary and if it's something that we do not want to get scraped and crawled, ultimately then it shouldn't be accessible in the first place. This is a hypothetical situation.

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[Kaspar Siminsky]

If it's public, if it's accessible, it's going to get crawled. Ultimately, it's kind of like a binary choice. If we don't want stuff for stuff to be crawled, it probably shouldn't be crawlable to begin with. If it's crawled by some bots, chances are it's going to leak.

[Tyson]

Ultimately, that's going to wrap up this episode of the Voice of Search podcast. Thanks again to Caspar Ziminski, senior Director at Search Brothers, for joining us. If you'd like to get in contact with Caspar, you can find a link to his LinkedIn profile in the show notes, or be sure to go over and check out his company's [e-mail] if you haven't subscribed yet and you'd like a daily stream of SEO and content marketing knowledge in your podcast feed, hit that subscribe button in your podcast app or on YouTube and we'll be back in your feed in the following day with that. That's all for today. Thanks for stopping by and we'll see

you on the next episode.