Modular llms.txt

Per-section llms.txt files let an agent pull more granular context.

Category: Content accessibility
Standard: Emerging; Off by default, turn on in settings

2%Top 100 adoption2 of 99 sites implement it 1/9OverviewStalledNo meaningful support, or vendors have said no.

Who supports it

No agent or browser has announced support yet.

27 others: no evidence yet. See every agent and browser

What it checks

The extension requests three section-level files:

/docs/llms.txt
/api/llms.txt
/developers/llms.txt

A file counts when it returns a successful response, is not HTML, and has an H1. The body is checked because a site that answers every path with a 200 would otherwise appear to have all three.

Results

Status	When
Pass	At least one of the section-level files was found
N/A	None of them was found

How to fix

If your site has distinct areas, such as documentation and an API, publish an llms.txt for each one at the root of that section, using the same format as the site-wide file:

# Example API

> REST API for Example accounting data.

- [Authentication](https://example.com/api/auth.md): Getting and refreshing tokens.
- [Invoices](https://example.com/api/invoices.md): Creating and listing invoices.

Related: llms.txt present.

Support by agent and browser

Announced means the vendor’s own docs or announcement say so. Published is the date on the vendor’s own page, where it has one. Checked is the last time our weekly research found that page still saying so.

No agent or browser has announced anything about this yet.

No evidence yet27

ChatGPT
Claude
Gemini
Perplexity
Copilot
Meta AI
ChatGPT Atlas
Comet
Dia
Gemini in Chrome
Edge Copilot Mode
Claude Code
Cursor
Codex
GitHub Copilot
Windsurf
CCBot
Applebot
Amazonbot
Bytespider
Cohere
Mistral
DuckAssist
Chrome
Edge
Firefox
Safari

Names and marks belong to their owners and are used only to identify products. None of these vendors is affiliated with Sitebulb. Spotted something out of date? Send a correction.

Adoption on the top 100 sites

2 of 99 measured sites implement it

Scanned 23 Oct 2026 with the Sitebulb Labs extension, against the Tranco list (tranco-56Z8N). 1 sites couldn’t be measured (bot challenge or timeout) and are left out of the share.

9 Oct 2026 1% → 23 Oct 2026 2%

Sites implementing it2

#93 bunny.net (via b-cdn.net)
#159 firebase.google.com (via crashlytics.com)

Overview

1/9

Stalled

No meaningful support, or vendors have said no.

How this rating is worked out1 of 9 points

Factor	Points	Why
Vendor support	0 / 3	0 vendors supporting, 0 partly or planned
Top-100 adoption	1 / 3	2% of measured sites
Spec maturity	0 / 3	Community proposal

8 or more points is Established, 5 to 7 is Gaining traction, 2 to 4 is Speculative and under 2 is Stalled. A feature is also Stalled when more vendors have said no than yes. Read the spec.

Community insights

No community insights for this feature yet.

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