The first crop of Apple Watch apps will likely be battery hogs, says a guy that tests iOS apps for a living

On Monday, Apple CEO Tim Cook is expected to announce a whole lot more details about the Apple Watch.

The big question is: what's the killer app for it?

Answer: There will be a lot of killer apps, because a lot of companies are already quietly working on apps for it, says Matt Johnston an executive for Applause, a Boston-based app-testing company.

Applause has not yet been able to test any of these apps because Applause does crowdsourced testing. It puts the app on hundreds or thousands of actual devices used in the real world, and that's how it finds the kinds of bugs, connectivity issues, battery life problems that the Average Joe will experience.

But the secrecy-loving Apple hasn't issued any actual advance devices to the broader development community. (Applause will start testing Watch apps the first day the Watch goes on sale.)

Applause works with companies like Google, Microsoft, USA Today, Trulia. He wouldn't dish on which specific companies are already working on apps, except to say "big household brand names." He did tell us the first crop of apps will be:

• Communication, social apps and mapping. In fact, the WatchAware blog has a list of about 20 Watch apps that have already been announced and these types of apps do dominate like: TL;DR for sending short emails; Yo, for sending a photo Yo or a location to your friends; Twitter; Facebook.
• Location-aware advertising/deal apps is something a lot of companies are working on, too.
• Travel apps. In fact, Apple has already demoed an American Airlines app and the Starwood app, which let's you check a reservation, check in and could even replace your hotel key).
• Obviously, fitness apps will be huge, too. And a number of them are listed by WatchAware, as well.

Interestingly, he's convinced that the first crop of apps will NOT be particularly buggy in the way they look. "I have every confidence that the apps will do a great job, with the user-interface rendering," he told us. Companies can test that kind of thing already using an Apple Watch simulator.

But he thinks they will be battery hogs. "The make-or-break issue is battery life and consumption," he says. That's because you can't test for that with a simulator.