Almost exactly a year ago, I measured how many of the top one million websites had adopted llms.txt, the web experience optimized for LLMs. Back then, the number was 1.22 %, or around 12k domains. A lot has happened in AI since then. Has adoption caught up?

Same measurement, one year later

I reused the exact same crawler implementation and the exact same classification rules as in 2025, applied to a fresh snapshot of the top one million domains taken on August 20, 2026. As a reminder, a response only counts as a valid /llms.txt if it satisfies all of the following conditions:

  • HTTP response code must be less than 400
  • Content-Type header must start with text/plain
  • The web server must accept the connection within 3 seconds
  • The response must arrive within 10 seconds
  • The site must support HTTPS
  • The response content must be longer than 500 chars
  • There must be more left square brackets than left angle brackets

See last year’s post why I ended up with these criteria.

Keeping the methodology fixed means the two runs are directly comparable, and any difference in the numbers reflects actual adoption rather than a change in how adoption is measured.

The measurement takes the same top 1 million domain list as last year, neglecting any changes in the popularity of the domains themselves.

Results

Adoption almost tripled. Among the top one million domains, around 35k now serve a valid /llms.txt. Overall adoption rate therefore is 3.53 %, up from 1.22 % last year.

Barchart comparing llms.txt adoption rate between 2025 and 2026 for the top n domains

The growth shows up at every popularity rank I looked at, from the top 100 domains to the full top million, with relative increases mostly in the 190-245 % range. The one exception is the top 300 domains, where growth was “only” 125 % — but that’s because the starting point there was already the highest in the dataset. The top 300 domains remain the best-adopting bracket by far, going from 4 % to 9 % adoption.

So while /llms.txt is still a minority practice even among the most prominent domains on the web, over 90 % still don’t serve one) the trend line is unambiguous. Whatever skepticism greeted the proposal a year ago, adoption is accelerating, not stalling.

The crawler, the analysis code, and the result dataset are available in the same Git repository as last year.