Create a url for a third party to create a new record

So I gather you were talking about a third-party app firing a web hook at Quickbase to create a record. 

It will need to have access to the app, so you will need to set up a usertoken under a real userid, ideally an account setup as a service account so it won't ever end up on the Deny list.

I would make the formula field on a table in your app to get it debugged and then expose the code by not giving the formula URL a label.

URLRoot() & "db/" & [_DBID_your target table alias goes here from advanced properties]

& "?act=API_AddRecord"

& "&usertoken=XXXXXXXXXXXXXXX"

& "&apptoken=YYYYYYYYYYYYYY" // only needed if you have left app tokens enabled for your app.

& "&_fid_100=" & urlencode("field value 1")

& "&_fid_101=" & urlencode("field value 2")

& "&_fid_102=" & urlencode("field value 1")