Third-party requests with HAR Desk
This opens a made-up checkout that loads an analytics pixel and a web font from other domains. The third-party filter is on, so only those requests are listed, and the Hosts box shows how the traffic splits.
- Load the HAR and open the Hosts box: each host with its request count and bytes.
- Tick Third party to keep only requests to other domains than the first page.
- Click a host to filter by it, then open a row to see who initiated the request when the browser recorded that.
- Open Sanitize if you want these hosts' URLs and query strings cleaned before sharing.
What to know
First party is taken to be the registrable domain of the first page loaded in the capture, and a request is third party when its domain differs. The domain is found by taking the last two labels of the host, or three for common country second levels such as co.uk. It is an approximation, not the public suffix list, so a site that serves assets from a separate domain it owns will show up as third party.
Third-party hosts matter for support in two ways. They are a frequent source of slow pages and blocked requests (a pixel stopped by an extension appears as status 0), and their URLs often carry identifiers in the query string, such as a user id on an analytics call. These are replaced by the parameter and pattern rules when you sanitize, but a parameter name that is not on the list is kept.
The Hosts box counts every request in the capture, not only the filtered ones, and sizes are the transferred bytes the file reports. Browser-recorded initiators (the _initiator field) are shown when present, which helps tell which script started a call.
Updated · Cosmovex
Questions
How is a request classified as third party?
By comparing its domain, the last two labels of the host, with that of the first page in the capture. It is an approximation and can misjudge sites that use several domains.
Can I see which script started a request?
When the browser recorded an initiator (Chrome writes _initiator), it is shown in the request detail.
Why does an analytics request show status 0?
Usually a blocker or privacy extension stopped it before it left the browser, so there is no response.
Will sanitizing remove the user ids in analytics URLs?
Parameters named like token, id_token, session or key are replaced, as are emails and token-like strings. An identifier under another name is kept unless you add a parameter rule.
The free plan covers everything on this page. HAR Desk Pro ($29, paid once) is described on the HAR Desk page.
