What this is
A free llms.txt validator: paste a URL and it fetches your /llms.txt and checks it against the llms.txt proposal (llmstxt.org) — file presence, plain-text vs HTML, a required H1 name, a blockquote summary, H2 link sections, and well-formed absolute links. It is a validator, not another generator. llms.txt is still an emerging proposal, so treat conformance as low-cost insurance, not a ranking lever. Updated 2026-06-14.
Frequently asked questions
What is llms.txt?
llms.txt is a proposed standard (llmstxt.org) for a markdown file at your domain root — /llms.txt — that gives LLMs a curated, link-listed map of your most important pages. It begins with an H1 project name, an optional one-line blockquote summary, and H2 sections of markdown links, with a special "## Optional" section for content that can be skipped to save context.
Does llms.txt actually do anything yet? (the reality check)
Be realistic: llms.txt is an emerging community proposal, not a ratified standard, and as of 2026 the major AI crawlers have not confirmed they read it. It is low-cost insurance, not a ranking lever. Treat it as a nice-to-have that may pay off later — and prioritize the fundamentals first: being server-rendered, crawlable, and well-structured, which is what our page-readiness linter checks.
What does this validator check?
It fetches your /llms.txt and checks conformance against the proposal: that the file exists and is served as plain-text markdown (not an HTML page — the single most common mistake), that it starts with a single H1 name, that it has a blockquote summary and H2 link sections, and that list items are well-formed markdown links using absolute URLs. It is a validator, not a generator.
Why does serving HTML at /llms.txt fail?
Many sites route every unknown path through their app, so a request for /llms.txt returns the site’s HTML shell with a 200 status. An LLM fetching that gets a page of markup, not your curated link list. The fix is to serve /llms.txt as a real static text file, the same way robots.txt is served.