Microsoft's acquisition of one of Germany's best startups will give it a pipeline into Apple

Wunderlist chief design officer Bendikt Lehnert was understandably quiet about the fact that his company was in talks to be bought by Microsoft for $100-$200 million when I met him in Berlin at the company's Alexanderplatz HQ two weeks ago. He was showing a pitch deck to about 20 tech journalists and didn't want to derail those talks by discussing the deal prematurely.

But he did drop a few interesting clues about what Microsoft will get from Wunderlist. The most interest part of is that Microsoft will get a new view inside Apple's App Store (and inside Slack, the work chatroom tool that is slowly replacing over office email).

Wunderlist has a good working relationship with Apple, Lehnert told us. Wunderlist was Apple's App of the Year in 2013, and "We were one of the first to launch on Apple Watch," Lehnert said. Wunderlist - with its various notifications - is "one of the few apps that actually makes sense on the device."

The company also prides itself on being "first to develop for each new iOS." It has also adopted Apple's simple, "beautiful" and highly focused design philosophy.

When Apple got a big wireless carrier deal in China and iPhone sales took off there, that almost instantly made China into a huge market for Wunderlist. "China became our second biggest market within a few months of launching there," he said.

Here is how the Wunderlist user-base breaks down:

• Total: 13 million users
• US: 30%
• China: 10%
• Germany 7%
• UK: 5%
• Netherlands: 2%
• Spain: 2%

"Before we started, Christian spent some time in China. He has a relationship with Apple," Lehnert said. The "Christian" he referred to is Christian Reber, the man who founded Wunderlist at age 24 in 2010.

"We have go-to people [at Apple] for almost everything," says Lehnert. ("Same with Google" and the Google Play app store.)

Since 2010, the startup has gathered $24 million in total investment funding.

It has also evolved into much more than a simple to-do list organiser. Wunderlist's Public API launched in May - that will give other software developers the ability to integrate or bolt-on aspects of their apps so that they can work with Wunderlist.

The company just launched an integration with Sunrise, the Microsoft-owned calendar app. (In retrospect, that was a clue to Microsoft's interest in Wunderlist.) Other "exciting integrations launching very soon" include Slate, OneNote, Hipchat, Zapier, and Scanbot, Lehnert said.

But perhaps the most exciting will be with Slack. Wunderlist's Slack integration will make Slack more searchable, Lehnert says. "Slack search is very powerful."

One way to think about that is to consider how useful it is to be able to search your own email. Slack is a direct messaging/chatroom platform for offices and work teams that largely replaces email, because it only contains messages from your colleagues. Outsiders end up being consigned to your email inbox. Slack user find, over time, that Slack is where important, immediate messages end up and email becomes more like a collection device for for second-rung messages that no one really wants.

Wunderlist is also poised ‚ but not quite ready - to become a full-bore enterprise product that can be rolled out across large businesses. There are 90,000 teams on Wunderlist. The paid version of the app costs $4.99 per user per month.

"We infect one person and then that person infects a team. Sometimes the CEO is that person and says 'hey can I have 16,000 seats?' And we say 'woah, we're not ready for enterprise! But we'll support you if we can,'" Lehnert says.