I was expecting a nice easy @command([OpenXpage];"Home.xsp") or uiw.openxpage command but no there isn't one. Here is how to do it.

To open the Home.xsp Xpage into your favourite browser from the Lotus Notes Client you can use code such as:

REM "Code from http://NotesNinjas.com/#OpenXpageFromClient";

r:=@DbLookup("";@Subset(@DbName;1):"names.nsf";"($Servers)";@Subset(@DbName;1);"HTTP_HostName");

s:=@If(@IsError(r) | @Text(r)=""; @DbLookup("";@Subset(@DbName;1):"names.nsf";"($Servers)";@Subset(@DbName;1);"SMTPFullHostDomain"); r);

@URLOpen("http://"+@Text(s)+"/"+@WebDbName+"/Home.xsp";)

To open an Xpage in the Notes Client do this instead:

REM "Code from http://NotesNinjas.com/#OpenXpageFromClient";

@URLOpen("Notes://"; + @Name([CN]; @Subset(@DbName; 1)) + "/" + @Text(@ReplaceSubstring(@ReplicaID; ":";""))+"/Home.xsp?OpenXpage")

This is the lotusscript version of opening an xpage in the client, stick it in a button.

' Lotusscript version from http://NotesNinjas.com/#OpenXpageFromClient

 Dim s As New  notessession
 Dim db As notesdatabase
 Set db = s.CurrentDatabase
 Dim sname As New NotesName(db.Server)
 
 notesurl = |notes://| +  sname.common+ "/" + Cstr(db.Replicaid) + "/Home.xsp?OpenXPage"
 Dim uiw As New notesuiworkspace
 Call uiw.URLOpen(notesurl)

NB you need the ?OpenXPage bit in there for it to work