SAN FRANCISCO ­ —

Though Satya Nadella did not appear during the keynote on the second day of Build, a certain spirit of openness some attribute to the new Microsoft CEO seemed to pervade the announcements.

On Thursday, in a keynote centered on advancements in the company’s tools and cloud services for developers, the executives onstage at the annual conference also made sure to emphasize the cross-platform capabilities of its offerings and even made open source one of its largest pieces of code.

To be sure, many of these projects were going on under former Microsoft CEO Steve Ballmer, said analyst Al Hilwa with research firm IDC.

“But it seems to have accelerated under Satya,” Hilwa said. “There’s a change in attitude toward other platforms. They’re changing their business model more aggressively.”

Among the announcements Microsoft made Thursday:

• The introduction of Azure Preview Portal, which brings together infrastructure and platform services and integrates Microsoft’s and third-party services of the user’s choice, allowing developers and IT workers to create and manage apps in one place.

Azure is Microsoft’s cloud platform.

• The general availability of Visual Studio Online, the online version of the environment developers use to create applications. Included are a lightweight editor to make code changes without having to leave Azure, the ability to debug in Visual Studio also without leaving Azure, and Application Insights, which gathers data on an application’s health and allows for easy retrieval of that data.

• The open-source availability of the .NET compiler platform (code-named “Roslyn”).

.NET is the Microsoft programming framework used by many developers to create Windows applications. A compiler translates code from the language the programmer uses to the language a machine uses to run a program.

Making the .NET compiler platform open source enables developers to see and tinker with something that has historically been proprietary.

Hilwa, the IDC analyst, said: “This technology is probably the single biggest piece of code Microsoft has put in open source, ever. It’s a major technology.”

He sees the move as symbolic of a more open Microsoft, given Microsoft’s historic antagonism toward open source.

Similarly, in their presentations Thursday, Scott Guthrie, head of Microsoft’s Cloud and Enterprise group, and other executives made sure to provide examples of how developers can use the company’s tools to create apps not just on Windows, but also on iOS, Android and Chrome.

“Azure as a hosting platform already supports multiple operating systems, including Linux,” said IDC analyst Al Gillen. “The message I heard today was about taking that to another level — taking the developer experience to a more cross-platform environment.

“Historically, Microsoft developers have developed only for the Windows environment,” Gillen said. “And developers who are interested in cross-platform deployment tended to use non-Microsoft tools. Microsoft today realizes that they need to have those cross-platform developers in their camp. And the only way they can do that is by offering a cross-platform set of solutions.”

Several developers at Build said they were heartened by Microsoft’s shift in tone toward emphasizing multiple platforms. But they also greeted it with a dose of skepticism.

During Thursday’s keynote, “there was so much reference to it [cross platform] but there weren’t many demos of it,” said Senthil Jayaraman, principal engineer at semiconductor-maker Broadcom. “I think that’s the direction Microsoft wants to go in, but there weren’t many examples of it.”

Jayaraman said he would have liked to have seen more examples of intricate games designed using Microsoft’s tools, not just browser apps.

“The direction is good, but there is no material to support it yet,” he said.

Microsoft last week signaled it was far more open to going cross-platform when it launched Office for iPad before it was ready for its own Windows tablets.

“I think the CEO shift at Microsoft is coming to even fuller clarity today with Microsoft’s announcement that they are putting the core technology inside the .NET platform, namely the language compiler, into open source,” Hilwa wrote in a note Thursday.

“This and wholeheartedly supporting customers and partners who run on other mobile platforms but use part of Microsoft’s technology stack, specifically the Microsoft Azure cloud, are indicators of the shift in leadership.”

Janet I. Tu: 206-464-2272 or jtu@seattletimes.com. On Twitter @janettu.