llms.txt Validator: Check Format, Links & Size

Your llms.txt

Site address

Fetch sends this address to leej.uk, which reads /llms.txt (and checks /llms-full.txt) once as LeejTools/1.0 and keeps only a count. Or paste below: pasted text never leaves your device.

llms.txtPaste the file, or Fetch it from your site.

Check

Outline

Links per section

Links

Section	Name	URL	Notes	Check

Cleaned llms.txt (absolute links, duplicates removed, Optional last)

llms.txt is a proposal from llmstxt.org. No AI company has committed to reading it; it costs little to add and doesn't affect search rankings.

Want the AI crawler view of your whole site? Run PingAI, which scores how well ChatGPT, Claude, Perplexity, Gemini and Copilot can reach and read it.

What it does

Parses llms.txt by the llmstxt.org format, flags structure and link problems, estimates size in tokens and writes a cleaned-up file.

H1, > summary, ## sections and the Optional section
List items checked as - [name](url): notes
Relative, http, duplicate and off-site links
Size and a token estimate; spots llms-full.txt

Private by design

Everything you paste or upload stays in your browser. Only when you press Fetch does leej.uk read the address you give, once, as LeejTools/1.0, keeping nothing but a daily count.

What you get

A checked outline and a cleaned llms.txt, with a Copy and a Download button on every result.

llms.txt
AI visibility
Markdown

Why it matters

llms.txt is a short Markdown file at the root of a site that tells AI assistants what the site is and which pages matter, in the format proposed at llmstxt.org: a title, a one-line summary and lists of links under headings. It's easy to get subtly wrong: relative links that break out of context, the same page listed twice, prose where links should be, or a huge file that should have been llms-full.txt.

This validator reads the file line by line against that format and shows the outline the way a parser sees it, every link with its problem, and a cleaned-up copy. Be clear-eyed about it: no AI company has promised to read llms.txt. It's cheap to add and harmless, and a tidy one is more likely to be useful if they do.

How it works

InputYour llms.txt, pasted or fetched
In your browserParsed against the llmstxt.org format
OutputErrors, link checks and a cleaned file

Where it fits in a designer's workflow

Plan
Design
Build
Test
Launch

Getting a site ready for AI assistants.

By the numbers

From this tool's checks on its sample file: 1 error, 2 warnings. 3 sections, 8 links, 747 B, about 187 tokens (characters ÷ 4, an estimate). The format is a proposal (llmstxt.org), not a standard any AI company has said it reads, so treat it as cheap insurance. Source: llms.txt proposal.

Show the numbers as a table

Link	Check
Dining tables	ok
Chairs	relative
Sideboards	ok
Dining tables	duplicate
Caring for oak	ok
Delivery	ok
Returns policy	ok
Our story	ok

How to use it

Paste your llms.txt, or enter your site and press Fetch.
Fix the errors first (red), then the warnings.
Check the links table for relative and duplicate links.
Download the cleaned file and upload it to /llms.txt.

FAQ

Is llms.txt a standard?

It's a proposal from llmstxt.org, used by a growing number of sites and documentation tools. No search engine or AI company has committed to using it.

What's the difference from llms-full.txt?

llms.txt is a short index of links. llms-full.txt holds the full text of the important pages in one file. Build one with the llms-full.txt Builder.

Why are relative links a problem?

AI tools often read the file out of context, without knowing which site it came from, so /tables means nothing. Full URLs always work.

Does it change my robots.txt?

No. llms.txt doesn't control crawling. Use robots.txt for that.

Work with me

Want a site that gets these right?

I build fast, accessible websites and web apps that pass these checks from day one. Tell me about your project and I'll reply personally with honest next steps.

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