I can get you this far. I found USPS web page that when it opens cursor is in an entry box. Unfortunately, can't get it to execute the search. User has to click button on web page. Set a VBA library reference to Microsoft Internet Controls.
Code:
Private Sub tbxZip_AfterUpdate()
Dim oBrowser As InternetExplorer
Set oBrowser = New InternetExplorer
oBrowser.Silent = True
oBrowser.Navigate "https://tools.usps.com/go/ZipLookupAction!input.action"
oBrowser.Visible = True
Do
'Wait till the Browser is loaded
Loop Until oBrowser.ReadyState = READYSTATE_COMPLETE
SendKeys "{tab}{tab}{tab}{tab}" & Me.tbxZip & "{tab}", True
End Sub
Even if could force the search, no idea how to parse the data from the results page. Then there is the issue of closing the page. I don't think VBA can selectively close a web page, have to kill all instances of the browser. I also can't get code to work with any other browser.
As I said earlier, not easy, if at all.