Free LLMs.txt Validator
When your llms.txt does not read the way you meant it to
It is easy to write an llms.txt that looks fine to a human and is awkward for a parser. A stray heading level, a list item without a proper link, a relative address or a title that is not on the first line can all make the structure harder to read for the tools that use it. This validator checks the file the way the proposal describes it and tells you exactly which line to look at. Below is a deliberately flawed file and what the tool would say about it.
Our Shop
## Products
- Mugs
- [Bowls](/bowls/)
### Sale
- [Plates](https://example.com/plates/)
- [Plates](https://example.com/plates/)The tool would report that the file does not start with a single H1 title, that the Mugs line is a list item without a link, that the Bowls link is relative, that the third level heading is not part of the format, and that the Plates link is listed twice. Five small problems, each with a line number.
How to use the validator
- Copy the file’s contents from
yoursite.com/llms.txt, or click Open a file. - Paste it into the box. Results update as you type.
- Read the counts at the top: sections, links, errors and warnings.
- Fix errors first, then warnings, using the line numbers.
- Check the preview under How it reads, to see the title, summary and sections as a reader would.
What counts as an error, a warning or a note
| Level | Examples |
|---|---|
| Error | No H1 title on the first line, or a link whose address is not a valid URL |
| Warning | More than one H1, missing summary, relative link, duplicate link, empty section, a list item that is not a link, deeper headings |
| Note | Plain text or quotes inside a section, which is allowed but unusual |
Code blocks marked with triple backticks are skipped, so example code inside your file does not cause false alarms.
Fixing the usual problems
- No title. Make the first non-blank line a single hash and a space, followed by your site name.
- List item without a link. Turn it into
- [Name](https://full-address): short noteor remove it. - Relative links. Use the full address with https, because the file is read away from your site.
- Duplicates. List each address once, in the section where it fits best.
- Deeper headings. Use H2 sections only, and put sub-groups into separate sections.
The Optional section
The proposal gives a special meaning to a section named Optional. Links placed there can be skipped by a tool that is short of space. Use it for secondary material such as an About page or old announcements, and keep the essential pages in the other sections. The preview marks the Optional section so you can see how it will be treated.
What validation does not prove
A clean result means the structure matches the proposal. It does not mean your links work, or that any AI product will read or reward the file. The tool does not open your addresses, so check them with a link checker or by clicking through them yourself. llms.txt is a proposed convention rather than an official web standard, and has no known effect on search rankings.
A good file, for comparison
# Sunrise Bakery
> Family bakery in Dhaka selling bread and custom cakes.
## Menu
- [Bread](https://example.com/bread/): Daily loaves
- [Cakes](https://example.com/cakes/): Custom orders
## Optional
- [Our story](https://example.com/about/)Paste this into the validator and you should see two sections, three links and no errors or warnings. Use it as a baseline when your own file produces messages you do not understand.
How often should you validate?
Every time you edit the file, and after any site restructure that changes addresses. A quick validation takes seconds, and catching a typo before upload is much easier than finding it later.
Before you upload
When the validator is happy, save the file as plain text named exactly llms.txt, upload it to the root of your domain, and open it in a browser to confirm it displays. If you need to start from scratch, the llms.txt generator builds a file from a form, and the AI crawler access checker shows which AI crawlers your robots.txt lets in.
FAQ
A single H1 title first, an optional quote summary, and H2 sections containing Markdown link lists.
No. It checks the format of each link but does not open them.
Yes. The proposal treats links under an H2 named Optional as ones that can be skipped when a tool has limited space.
No. There is no evidence that it affects search rankings.
No. It is checked in your browser.
Yes. It should be a plain text file called llms.txt, placed at the root of your domain.