I am using ChroPath for more than 18 months. It is a very good tool for generating and verifying xpath and cssselector.
It can also be used as an Editor to write your own XPath and CSS Selector. It makes it easy to write, edit, extract, and evaluate XPath queries on any webpage. ChroPath Studio helps to record all manual steps along with automation steps. With smart maintenance features, all XPaths can be verified from script in a single shot. ChroPath also supports iframe, multi selectors generation, dynamic attributes, and generates relative XPath with custom attributes, automation script steps, and many more.
You can refer below video to see live example on how to use this extension.