Is there any kanji to radical converter online tool or app is there?

[Powerpuncher]

You should also check out the resources list here on the forums

The Ultimate Additional Japanese Resources List!

This post is a list of Japanese resources and stands as a collaborative wiki gathered by the WaniKani Community. If there’s a resource you feel is missing from the list, please add it by clicking the edit button above. Include an edit reason by clicking the button at the top of the edit window. Many of the resources here are free, however, the ones that aren’t are marked with a dollar sign $ or otherwise noted. Click on the triangle symbol ► to open a section’s resou…

A ton of resources for pretty much anything you want to learn more about.