How to check if your llms.txt is working

llms.txt Guides · November 3, 2026 · 6 min read · By Mobilize Cloud

To check if your llms.txt is working, you need to confirm three things: the file is actually there as plain text, it follows the llms.txt format, and the pages it links to still exist. You can do the first in your browser in ten seconds. Our free llms.txt validator does all three and tells you in plain English what to change.

This guide walks through each step, explains what the score and the fixes mean, and covers how to keep the file working after you've published it.

Step 1: Open the file in your browser

Type yourdomain.com/llms.txt into your browser's address bar. You should see plain text: a line starting with # and your business name, then a short summary and lists of links. No menus, no images, no styling.

If you see your normal website instead, such as your home page or a "page not found" design, the file isn't there. Many websites show a page for any address they don't recognize, so a page loading doesn't mean the file exists. That one catches a lot of people out, and it's common on WordPress when a plugin catches the address before the file can load.

Step 2: Run it through the llms.txt validator

Go to the llms.txt validator, type your website address (just yourdomain.com is enough) and press Check llms.txt. No account is needed. We fetch the public file, check it against the llms.txt proposal and show the result.

Haven't published yet? Open Or paste a file to check it before you publish and paste the contents instead. That's the safest way to catch mistakes before anything goes live.

Step 3: Read your score

At the top of the result you'll see the title we found in your file, your summary line, and a score out of 100 with a one-line verdict:

Score	Verdict	What it means
80 to 100	Looks good	The file follows the format. Any remaining items are small.
50 to 79	Needs a few fixes	The file works, but something is making it harder to read.
Under 50	Needs work	There's a structural problem, such as a missing title.
No score	No llms.txt file yet	We found an empty response or a web page, not a text file. This counts as 0.

The scoring is simple and published on the validator page. Every file starts at 100. Each "must fix" problem costs 40 points, each "should fix" costs 10, and tips cost nothing. A problem counts once however many lines it affects, so one repeated quirk won't sink a large file. Below the score you'll also see a quick count, for example "3 sections listing 9 pages. 2 things to fix."

Step 4: Work through the fixes

Each problem is listed with a label, a plain-English description and a How to fix line. The labels tell you what to do first:

Must fix: problems that stop the file being read properly, such as a missing # Title line or a title that isn't on the first line.
Should fix: problems that make the file less useful, such as links with no https://, a section heading with no pages under it, or only one or two pages listed.
Tip: suggestions that cost no points, such as adding a one-line summary or using full addresses instead of short ones like /pricing.

Most problems also show a line number. When we checked a live file, the line number is a link: click it and the validator opens The file we checked, a copy of your file with numbered lines and the problem lines highlighted. That makes it easy to find "line 14" in a long file, especially one a plugin generated.

Not the person who edits the file? Press Email these fixes to my developer. It writes an email with every problem, how to fix it and a link to the full report. You can also press Copy link to this report and share it however you like.

For a deeper look at the usual culprits, see 10 common llms.txt mistakes and how to fix each one.

Step 5: Check the content type

When your browser or an AI tool asks for a file, the server answers with the content plus a label saying what kind of content it is. For llms.txt that label should be text/plain or text/markdown. If your server sends something else, the validator shows a "Served with the wrong type" warning.

You can see the details yourself by opening Technical details under the result. It shows:

HTTP status: 200 means the file was found. 404 means it wasn't.
Content type: the label your server sent.
Size: how big the file is. Keep llms.txt well under 1 MB; longer content belongs in llms-full.txt.
llms-full.txt: whether you also have the optional longer file, and how many links it holds.

A wrong content type is usually caused by a plugin, a redirect or a CDN rule rather than the file itself. Your host can normally fix it in a few minutes. Developers can also pull the whole report as JSON from the link in this panel.

Step 6: Check that the links work

A perfectly formatted file can still point to pages that no longer exist. Below the fixes, press Check the links. We open each page your file links to (up to 40) and report any that fail, with the reason: page not found, blocked or needs a login, server error, or couldn't connect.

Broken links are common after a redesign or when pages get renamed. The fix is to update the address in your file or remove the line.

What "working" can and can't tell you

A high score means your file is correct and readable. It doesn't tell you whether a particular AI tool has read it, or what it did with it. AI companies haven't said much about how they use llms.txt, and we cover the evidence in does anyone actually use llms.txt? What you can control is that the file is there, accurate and easy to read. The validator checks exactly that.

If you want a wider view, the free AI readiness check looks at your whole site: whether AI crawlers are allowed in robots.txt, whether your content is visible without JavaScript, structured data, your sitemap, and your page title and description.

Keep it working: monitoring

Passing the validator once is a good start, but files break quietly. A plugin update, a theme change, a site migration or a new CDN rule can replace your llms.txt with a web page, and nothing on your site will tell you. Plugin-generated files also change on their own as you publish.

That's what listing on LLMs Ledger is for. Add your site and we'll re-check the file on a schedule:

Free: llms.txt checked every 3 months and AI readiness monthly, with a small "Listed on LLMs Ledger" badge on your site.
Monthly ($9/mo): monthly checks, weekly AI readiness, version history and an email if the file breaks.
Nightly ($19/mo): checked every night, with an email showing exactly what changed and nightly link checks.
Agency ($79/mo per 10 sites): every client site in one dashboard, checked nightly, with one daily summary email.

We never change your website or your file. We only read the public file you publish. Cancel any time.

Bottom line: open the file in your browser, run it through the validator, fix anything marked "must fix" or "should fix", and check the links. Then set up monitoring so you hear about it when something breaks, instead of finding out months later.