- [ Home ](/) / - llms.txt format # `llms.txt` Format, Spec Reference The complete reference for the llms.txt file format: required and optional elements, Markdown rules, link syntax, the llms-full.txt variant, and a checklist to validate your file. Last updated: August 12, 2026 On this page - [ Format overview ](#overview) - [ Required elements ](#required) - [ Optional sections ](#sections) - [ Link syntax ](#links) - [ llms-full.txt variant ](#llms-full) - [ Checklist ](#checklist) - [ Common mistakes ](#mistakes) ## Format overview `llms.txt` is a plain-text resource using [CommonMark Markdown](https://commonmark.org/). It may live at the origin root or a more specific path such as `https://example.com/docs/llms.txt`. The most specific applicable file describes that scope. Compatible coding assistants, RAG pipelines and research agents can use the file as a curated map. Publication alone does not prove discovery or use, so declare it with `rel="describedby"` where appropriate and measure the clients you actually support. ## Required elements The August 2026 proposal defines one mandatory element: - **H1 heading**, the first line must be an H1 (`# Name`) containing the project or site name. The blockquote summary, explanatory preamble, H2 file lists and link notes are optional. Minimal valid llms.txt Copy ``` # Your Project Name > One sentence describing what your project does and who it's for. ## Documentation - [Getting Started](https://example.com/docs/start): Install and first steps. - [API Reference](https://example.com/api): Full endpoint catalog. ## Optional - [Changelog](https://example.com/changelog): Release history. ``` ## Optional sections Sections are H2 headings (`##`) followed by unordered lists of Markdown links. Common section names include: - **Documentation**, primary docs, guides, references. - **Product**, marketing pages, pricing, status. - **Examples**, code samples, tutorials, demos. - **Optional**, changelog, blog, GitHub, lower priority for AI. - **API**, dedicated API reference section. - **SDKs**, language-specific client libraries. **Optional** remains a clear editorial label for secondary resources, but v2 assigns it no special processing semantics. Full example llms.txt Copy ``` # Acme SaaS > Acme SaaS helps teams automate their billing workflows with a no-code dashboard > and a REST API supporting 40+ payment providers. ## Product - [Overview](https://acme.com/product): Core capabilities and use cases. - [Pricing](https://acme.com/pricing): Plans, limits, and enterprise options. - [Status](https://status.acme.com/): Uptime and incident history. ## Documentation - [Quickstart](https://acme.com/docs/quickstart): Set up in under 5 minutes. - [API Reference](https://acme.com/docs/api): REST endpoints, auth, rate limits. - [SDKs](https://acme.com/docs/sdks): Node, Python, Ruby, Go clients. - [Webhooks](https://acme.com/docs/webhooks): Event payloads and retry policy. ## Examples - [Node.js integration](https://acme.com/examples/node): End-to-end payment flow. - [Python integration](https://acme.com/examples/python): Subscription management. ## Optional - [Changelog](https://acme.com/changelog): Version history. - [Blog](https://acme.com/blog): Product updates and tutorials. - [GitHub](https://github.com/acme/acme-oss): Open-source components. ``` ## Link syntax Each link follows the Markdown syntax `- [Title](URL): short description.` - Use **absolute URLs** including the scheme (`https://`). - The description after the colon is plain text, keep it under ~120 characters and make it informative for an AI, not keyword-stuffed. - One link per list item, do not nest bullets. - Prefer canonical URLs (with trailing slash if that's your convention). Example Write descriptions for AI readers Unlike HTML alt text or SEO meta descriptions, the link descriptions in llms.txt are read by language models building a mental map of your project. Be precise: "Full REST endpoint catalog with auth and rate-limit details" is more useful than "API docs". ## llms-full.txt variant The wider ecosystem uses an optional companion file at `/llms-full.txt`. While `llms.txt` is an index of links, `llms-full.txt` contains the *full text* of those linked pages concatenated together, formatted in Markdown. A tool that explicitly supports the convention may fetch `llms-full.txt` for consolidated context. The trade-off is greater size, staleness and security exposure. Read the dedicated [llms-full.txt guide](/llms-full-txt/) for generation strategies. ## Checklist - File served at the root or the intended scoped path - Plain-text or Markdown media type with UTF-8 encoding - Starts with exactly one H1 heading - Optional blockquote and preamble contain no headings - Link targets resolve correctly in their publication context - Optional link notes are concise and factual - File size is justified by the tasks and tested clients - No HTML tags, no nested lists - Validated with the [llms.txt validator](/validator/) ## Common mistakes - **Relative URLs**, `- [Docs](/docs)` will not resolve correctly when the file is fetched by an AI crawler. Always use absolute URLs. - **Missing blockquote**, this is not a v2 compliance error. Add one only when a short factual summary helps the intended client. - **Wrong Content-Type**, serving with `text/html` or no content-type causes some parsers to reject the file. - **Keyword stuffing descriptions**, AI models read these literally. Stuffing keywords degrades the quality signal. - **Listing every page**, curate your most important 10–30 links. Use `sitemap.xml` for exhaustive URL discovery. A companion `llms-full.txt` may bundle content for explicitly compatible ingestion workflows, but it does not replace a sitemap. ## Related guides - [How to create llms.txt](/how-to-create/), step-by-step for any stack. - [llms-full.txt guide](/llms-full-txt/), full-content companion file. - [Validator](/validator/), check your file for spec compliance. - [Generator](/generator/), create a file from a form. - [Best practices](/best-practices/), what to include and what to skip. - [Which AI crawlers read llms.txt](/llms-txt-ai-crawlers/), adoption status. ## Sources - [ llmstxt.org, community proposal ](https://llmstxt.org/) - [ Answer.AI, original proposal ](https://www.answer.ai/posts/2024-09-03-llmstxt.html)