New York: Software developers say it will not be easy to come up with a "killer app" for Apple Inc's Watch - few have seen the product and the software is still in test mode.

While app makers are passionate about developing for the Apple Watch, some are skeptical about the prospects of coming up with a big idea for the little computer on a wrist that hits stores on April 24, said Markiyan Matsekh, product manager at software engineering firm Eleks.