Who really supports llms.txt?
The answer is less comfortable than most vendors admit — and more interesting than the headline “Google doesn’t want it” suggests. Here is the status per system, every row with a source and a date.
The short version
Not one vendor guarantees it reads your llms.txt
Google says no, explicitly. Its official guide to generative AI features in Google Search (15 May 2026) states that additional machine-readable files “neither harm nor help your site’s visibility or rankings”.
Everyone else stays silent — but uses the format themselves. Anthropic, OpenAI, Perplexity, Mistral and xAI all serve their own developer documentation as an llms.txt. A company that picks a format for its own docs clearly considers it useful.
What follows: an llms.txt is neither a ranking lever nor a magic trick. It is an offer to the systems that do fetch it — and a discipline that makes your content better for any machine processing. Anyone promising more is selling hope.
Status per system
Official stance — and who runs an llms.txt themselves
Two questions that constantly get mixed up: does the vendor say it reads llms.txt? And does it use the format itself? We check the second column automatically every day — you can open every URL yourself.
| System | Official stance | Publishes one? |
|---|---|---|
| Google SearchAI Overviews · AI Mode | Explicitly does not use llms.txt. In its official guide to generative AI features, Google states you do not need “new machine readable files, AI text files, markup, or Markdown” to appear in Google Search — such files “neither harm nor help your site’s visibility or rankings”. Google Search Central, generative AI guide · May 15, 2026 — publishes none (HTTP 404) |
— HTTP 404 |
| Anthropic · ClaudeClaude, Claude Code | Uses the format itself, but guarantees no fetching. Anthropic publishes its own developer documentation as an llms.txt and, in its engineering post “Writing effective tools for AI agents”, points to the format as the common place for LLM-friendly documentation. That is not a commitment to automatically fetch third-party llms.txt files. Anthropic Engineering · Aug 19, 2026 ✓ publishes an llms.txt · view |
✓ view |
| OpenAI · ChatGPTChatGPT search, OAI-SearchBot | No official commitment — but publishes one itself. OpenAI has never committed to consuming llms.txt. Retrieval runs through its own crawlers (OAI-SearchBot, ChatGPT-User) and through the Bing index. OpenAI’s own developer documentation, however, is served as an llms.txt. OpenAI developer docs · Aug 19, 2026 ✓ publishes an llms.txt · view |
✓ view |
| PerplexityPerplexityBot | No official commitment — but publishes one itself. Perplexity crawls sites in the classic way and makes no statement about evaluating llms.txt specifically. Its own documentation is available as an llms.txt. Perplexity docs · Aug 19, 2026 ✓ publishes an llms.txt · view |
✓ view |
| Microsoft Copilot · BingBing index, Copilot | No commitment — the Bing index is what counts. For Copilot — and for ChatGPT’s web retrieval — what matters is whether a page is in the Bing index, not whether it has an llms.txt. Since February 2026 Microsoft has shown a dedicated AI citation report in Bing Webmaster Tools. Bing Webmaster Tools · Feb 10, 2026 — publishes none (HTTP 404) |
— HTTP 404 |
| MistralLe Chat | No commitment — publishes one itself. No public statement on consuming third-party files; its own documentation is provided as an llms.txt. Mistral docs · Aug 19, 2026 ✓ publishes an llms.txt · view |
✓ view |
| xAI · GrokGrok | No commitment — publishes one itself. No public statement on consuming third-party files; its own documentation is provided as an llms.txt. xAI docs · Aug 19, 2026 ✓ publishes an llms.txt · view |
✓ view |
Stance column editorially reviewed on Aug 19, 2026. Live column: 5 of 7 vendors checked so far serve an llms.txt on their documentation domain — automated check, every 24 hours.
What to do instead
The four things that measurably work
If llms.txt is not a ranking lever — then what? Everything the systems demonstrably use to pick sources:
The most common mistake: robots.txt blocks GPTBot or ClaudeBot, often unnoticed via a separate user-agent group. Without access, nothing else matters.
AI crawlers do not execute JavaScript. What is not in the raw HTML does not exist for them — even if the page ranks first on Google.
A machine-readable modification date and real updates. Answer engines prefer demonstrably fresh sources.
Clear headings, lists, tables, sourced numbers. RAG systems cite passages, not walls of text.
We check all four automatically: the AI crawler check for access, the AI check including citability for the rest. Both free.
FAQ
llms.txt and the AI systems
Does Google read my llms.txt?
No. In May 2026 Google explicitly stated that additional machine-readable files are neither required nor helpful for visibility in Google Search and its AI features. Anyone selling you an llms.txt for Google visibility has not read the guidance.
So why have an llms.txt at all?
For three reasons that hold even without Google: first, assistants and developer tools do fetch the file when they know about it. Second, a good llms.txt forces you to structure your content clearly, which helps every kind of machine processing. Third, the AI vendors use the format for their own documentation, which suggests continued relevance.
Where does the “publishes one” column come from?
From an automated check: once a day we request each vendor’s documentation domain at /llms.txt and record whether a valid file is served. That is objectively verifiable — you can open the linked URLs yourself.
How current is this page?
The stance column is editorially maintained and carries a source and date per row. The live column checks itself daily. If an official statement changes, we change the row — not the marketing.
Does llms.txt replace robots.txt?
No, it complements it. robots.txt governs what crawlers may not do; llms.txt offers what should be read. If your robots.txt blocks AI crawlers, the finest llms.txt is useless — by far the most common mistake.
First check whether AI can get in at all
The crawler check reads your robots.txt against 20 AI crawlers — with real Google semantics, including the inheritance trap. Free, no signup.