10,877 sites implement Markdown negotiation
of 14,351 tested · measured 2026-08-23
every listed site fetched twice, 23 Aug 2026 · 14,351 listed
Checks passed across the 11,005 probed hosts: Markdown negotiation 10,877 · Markdown twin at a predictable URL 5,358 · llms.txt 8,809 · API catalog 3,541 · MCP server card answers 5,129.
10,877 pass when we test the behaviour. 4,372 do not.
Any directory can list sites that claim a standard — the claim is in the source and costs nothing. Separating the two requires testing the behaviour, and dating the result. That is the only thing on this page you cannot get elsewhere.
What Markdown negotiation is
A site that answers Accept: text/markdown with actual markdown hands an agent the content without the navigation, scripts and layout it would otherwise have to strip. The same URL, a cleaner representation. Read HTTP content negotiation (RFC 9110) — it is the authority on the design and we are not trying to be.
How we test it
We fetch the page twice — once as HTML, once with Accept: text/markdown — and compare. Since rubric v1.1 the check passes only when the body IS markdown AND differs from the HTML response.
A text/markdown content-type header on an HTML body was passing before v1.1. The header is a claim; the body is the evidence, and the two disagreed often enough to be worth re-probing the whole index for.
Sites that implement it
39.8% of these are on mintlify, 2.8% of these are on teachify. The platform supplies the machinery; the domain signals the commitment, and a report says which applies.
The 11,269 listed sites that negotiate markdown or ship a markdown twin, through the API — a wider set than the one this page counts: every one, in a fixed order, 25 per call, with the total stated.
Markdown negotiation is one signal among several. The rubric says exactly what we look for and how each tier is reached, and a probe can be requested — the probe decides, never the request.
Method and date
Measured 2026-08-23. every listed site fetched twice, 23 Aug 2026 · 14,351 listed Every figure on this page carries the population it was measured against; a count without a denominator is not a measurement. How the index is built · All standards.