Key in the URL of your xpage on the browser followed by a plus sign (+)
Now hit enter and there you go, you will be able to see the XPage source code on the browser
For example your url must follow the following format http: //server/dbpath/xpageName.xsp+
Illustration: refer to the following figure
Note: This works only with IE.In case of Firefox and Chrome, it results in the download of a file with an extension "xsp"
Edit: This shall be helpful for development purpose. You will be able view the source code only if you have Manager or designer access to the database that you have in your own server or local. Hence this would fail for public sites like ideajam.net etc... This simply wont work