There are n number of xpath extension for chrome. But most of them are not perfect, they breaks in most of the cases like xpath helper, chropath, xpath finder etc.
But there is only one XPath extension which proven to work for all web elements and for all web applications SelectorsHub.
Best thing about SelectorsHub is that it used to keep getting regular updates.
It is the only XPath extension which supports shadow dom, nested shadow dom, nested iframe, svg elements and gives proper error message for invalid xpath.
It has smart editor feature which made it possible to write xpath within 5sec.
Another good thing it is available for all the browsers.