No signup, nothing stored. Checking somebody else's site is fine: this only reads what every visitor's browser already downloads.
This checks the page your address serves to a normal visitor, the same way a browser would, and it opens any Google Tag Manager container it finds and reads inside it. Nothing is stored, no signup is asked for, and the answer is the same one you would get by opening the page source yourself with more patience than most people have.
How to check this yourself, without any tool
Open your site in Chrome, right click, choose View Page Source, and search the page for fbq. If it appears, a pixel is loading directly in the HTML. If it does not appear, search for GTM- instead: a match there means your tags live inside Google Tag Manager and the page source will never show them, which is exactly where most checkers give up and hand you a wrong answer. The other reliable route is Meta's own Pixel Helper extension, which reads the page after scripts have run.
Installed is not the same as working
A pixel that only fires PageView tells Meta that a human loaded a page and nothing else. It never learns that anyone filled the form, called, or booked. Meta then optimises for the only outcome it can see, which is cheap visits, so you get more traffic and not more customers, and the reporting cannot tell you which ad produced work. This is the single most common state we find on live advertiser sites, and it looks fine from the inside because the dashboard is full of numbers.
Two pixels is worse than none
When an agency installs one and a website builder plugin installs another, both fire on every page. Events get counted twice, your reported cost per lead halves on paper, and you scale spend against a number that was never real. If the check above returns more than one pixel ID, that is what is happening, and removing the duplicate is usually a ten minute job.
Why the pixel misses more than it used to
Browser tracking prevention, ad blockers and iOS privacy settings all stop a browser side pixel from reporting. Depending on the audience, a meaningful share of real conversions never reach Meta at all, which shows up as your ads account claiming fewer leads than your inbox contains. The fix is server side tracking through the Conversions API, which reports from your server instead of from the visitor's browser.
Common questions
Does this find a pixel installed through Google Tag Manager?
Yes, and that is the main reason it exists. When a GTM container is present it is fetched and read through, so a pixel inside it is found. If a container is present but cannot be opened, the answer given is cannot tell rather than no.
Why does it say no pixel when Meta Events Manager shows activity?
Usually because the pixel is only on some pages, most often the thank you page, and not on the address you checked. Try the exact page your ads send people to. It can also happen when the pixel loads only after a cookie banner is accepted, in which case it is genuinely absent for anyone who does not accept.
Is a Meta Pixel and a Facebook Pixel the same thing?
Yes. It was renamed to Meta Pixel when the company was renamed, and the code still uses the function name fbq. Anything written about the Facebook Pixel applies unchanged.
Can I check somebody else's website with this?
Yes. It only reads what any visitor's browser already downloads, so there is nothing private in it and nothing that a competitor could not see by viewing your page source.