Microsoft's Cortana isn't the trendiest voice-activated personal assistant — that title goes to Amazon's Alexa — and its Azure public cloud plays second fiddle to Amazon Web Services.

On Tuesday at the company's annual Build conference in Seattle, Microsoft executives spent hours showing how they plan to change that.

CEO Satya Nadella also pointed out one edge that Microsoft still has over Amazon: its massive reach in enterprises. People who use Windows machines and Cortana are "the most valuable set of users in the core of the enterprise," Nadella said. People are using Windows 10 on more than 500 million devices every month, while Cortana now has 140 million monthly active users.

With the introduction of its Cortana Skills Kit, Microsoft is making it possible for outside developers to bring their services to Windows 10 as well as the company's Skype for Business video conferencing app and Bing search engine. In doing so, Microsoft is trying to make it more worthwhile for developers to build for Cortana, and open up its services for more third-party features. Also, longtime Microsoft partners HP and Intel will be working to build Cortana-enabled devices.