Third Party Resource Checker
List every other company a page loads from, what each costs in connection time, and who sees your visitors.
About this tool
Lists the origins a page pulls scripts, styles, fonts, images and frames from, grouped by company, with what each one appears to be.
There are two separate reasons to care, and they have different answers.
**Speed.** Every new origin costs a DNS lookup, a TCP connection and a TLS handshake before one byte of the actual resource arrives. On a mobile connection that is a few hundred milliseconds per origin, and no amount of minifying recovers it.
**Privacy.** Every third-party origin receives the visitor's IP address and the page they are on, whether or not the resource does any tracking. That is usually the disclosure a cookie banner is claiming to cover, so knowing the actual list is worth more than assuming it.
**Only what is in the HTML is visible here.** Anything injected later by a script — which is most of what a tag manager loads — cannot be seen from the markup, so treat this as a floor rather than a full inventory.
Common questions
Why does the number of origins matter more than the number of files?
Because files on an origin you have already connected to reuse that connection. A new origin means DNS, TCP and TLS again before anything downloads — commonly a few hundred milliseconds on mobile, regardless of how small the file is.
Why can it not see everything?
Because scripts add resources after the page loads, and reading the HTML happens before that. A tag manager is one script in the markup and can be twenty origins once it runs. Seeing those needs a real browser.
Is loading fonts from Google a privacy problem?
It has been treated as one in several European rulings, because the request discloses the visitor's IP address to a third country. Self-hosting the font files removes the question and is usually faster as well.
How do I reduce this?
Self-host fonts and libraries, remove tags nobody reads reports from, and use preconnect for the origins that genuinely have to stay. Cutting the list is nearly always easier than making each item faster.