# How common is llms.txt on AI-cited domains? | Trakkr Research

Canonical URL: https://trakkr.ai/trakkr-research/llmstxt-effect/answers/how-common-is-llms-txt-on-ai-cited-domains
Published: 2026-03-14
Last updated: 2026-03-14
Author: Mack Grenfell

It is still uncommon. Only 13.3% of the 37,894 scanned AI-cited domains had an llms.txt file.

## Methodology

Built from HTTP scans of 37,894 AI-cited domains, linked to 337,362 citations and 882 citation snapshots in the Trakkr corpus.

## Direct Answer

Rarely. Only 13.3% of the 37,894 scanned AI-cited domains had an llms.txt file.

## What this means

Operators must allocate technical SEO resources efficiently. Knowing the low adoption rate prevents teams from over-investing in this file at the expense of core content quality and structure.

## Evidence table

| Metric | Value | Why it matters |
| --- | --- | --- |
| Domains scanned | 37,894 | AI-cited domains scanned for llms.txt. |
| Adoption rate | 13.3% | Domains with llms.txt in the study. |
| Domains with llms.txt | 5,035 | Absolute adoption count. |

## Frequently Asked Questions

### How many AI-cited domains actually use llms.txt?

Out of 37,894 scanned domains, exactly 5,035 domains feature the file.

### Is an llms.txt file required to get cited by AI engines?

No. With an adoption rate of 13.3%, the vast majority of cited domains do not use the file.

## What to do next

- [Treat llms.txt as an optional housekeeping file rather than a primary citation-growth lever.](https://trakkr.ai/trakkr-research/llmstxt-effect/answers/how-common-is-llms-txt-on-ai-cited-domains#next-step-1)
- [Prioritize answer quality, source coverage, and page structure before spending disproportionate effort on llms.txt.](https://trakkr.ai/trakkr-research/llmstxt-effect/answers/how-common-is-llms-txt-on-ai-cited-domains#next-step-2)
- [Measure discovery and crawl behavior directly if you publish llms.txt instead of assuming it improves citation performance.](https://trakkr.ai/trakkr-research/llmstxt-effect/answers/how-common-is-llms-txt-on-ai-cited-domains#next-step-3)

## Related pages

Continue through the same study cluster.

- [is llms txt more common on top domains than the long tail](https://trakkr.ai/trakkr-research/llmstxt-effect/answers/is-llms-txt-more-common-on-top-domains-than-the-long-tail) - Related answer page
- [which industries adopt llms txt most](https://trakkr.ai/trakkr-research/llmstxt-effect/answers/which-industries-adopt-llms-txt-most) - Related answer page
- [median citations are identical with and without llms txt](https://trakkr.ai/trakkr-research/llmstxt-effect/facts/median-citations-are-identical-with-and-without-llms-txt) - Related fact page
- [llmstxt adoption by sector tracker](https://trakkr.ai/trakkr-research/llmstxt-effect/trackers/llmstxt-adoption-by-sector-tracker) - Related tracker page

## Data And Sources

- [The llms.txt Effect](https://trakkr.ai/trakkr-research/llmstxt-effect) - Flagship study behind this page
- [Page JSON](https://trakkr.ai/data/research-answers/llmstxt-effect/answers/how-common-is-llms-txt-on-ai-cited-domains.json) - Machine-readable companion file