Independent developers for Microsoft's platforms are increasingly concerned about the lack of clarity from the software giant over the future direction of its programming platforms such as Silverlight, Windows Presentation Foundation (WPF) and .Net compared to non-proprietary platforms such as HTML5, CSS3 and javascript.

The worries have grown following the demonstration of the Windows 8 interface at the AllThingsD event earlier in June, at which it emerged that there will be new APIs for writing apps for the touchscreen tablet-style form of the interface. In a video, Julie Larson-Green, the product manager for Windows – who determines which features are included and which are not – suggests that the APIs for the new touchscreen form of Windows will be "HTML5 and javascript".

That has worried developers, who devote a lot of time to choosing the best Microsoft tools to develop in, because it implies that if they want to program for the tablet form – which Microsoft is implying will be a key format in the future as it tries to catch up with Apple, Android and other tablets in the new form factor – then they will have to learn a new set of skills and perhaps abandon all their expertise.

Developers using Silverlight – a browser plugin similar to Adobe's Flash – have besieged Microsoft's support boards demanding clear answers. Jan Hannemann simply asked "Windows 8 apps going html5, wtf" and complains "I don't like that we are supposed to write Windows 8 apps in html/js. Wow, thats the stupids thing I ever heard. Microsoft has a first class cross-platform application framework called Silverlight and they want us to write freaking javascript. Really!? Probably the next version of WindowsPhone will run HTML5 as well. C'mon, I'm really disappointed." His post had more than 7m page views.

On another Microsoft developer forum, Nicholas Petersen of Eclipsoft called for Microsoft to explicitly include "full support" for WPF and Silverlight as well as HTML5 in Windows 8: "WPF and Silverlight developers have valid reasons to be concerned that the Microsoft .NET UI platforms they have grown to love and support – because they're the best in the world – are being demoted in Windows 8 in a way that could relegate them to a place of obscurity. This place of obscurity could even be a way of letting them 'die on the vine,' if indeed they were no longer put forth as platforms of the future, and supported as such. We would like to know: Do Silverlight and WPF have an integral, irreplaceable, and front-facing role to play in Windows 8 and in the future?"

Peterssen pointed out that "In all of the officially released statements concerning the upcoming Windows 8, there has not been one prepared statement that even mentions the future role of .NET, WPF, or Silverlight in Windows 8, contrary to all of the statements concerning the integral role the new HTML5 platform will play. Only after Windows president Steven Sinofsky was asked what role Silverlight played in Windows 8, was it stated that it would continue to run in IE and on the desktop. Clearly then, our concern is not that these terrific platforms will be terminated, but that they might be left to 'dry on the vine'."

He articulated a worry that Microsoft will draw a distinction in Windows 8 between "web-connected apps" – which will be built with HTML5 – and "existing Windows Apps", which will use WPF and Silverlight: "We do not want Silverlight and WPF apps to be relegated to a 'classic' (if even a "legacy") category". The worry is that .Net and Silverlight apps will be pushed down to a second-class existence and be unable to use the touch interface, and that developers would have to learn an entire new programming lexicon for HTML5/CSS3/javascript rather than their familiar ones of Silverlight, WPF and .Net.

Hundreds of developers have besieged the Silverlight forums seeking more information. But Microsoft has not responded – except to say that it will not respond before the Build conference for developers in September.

Peter Brown, the Microsoft community program manager for WPF, Silverlight, XNA, Windows Phone and others, posted: "This whole thing has blown way out of proportion. Base your information on our primary sources (like our press release), not on third-party speculation. That's not to minimise how everyone feels, but keep in mind that Windows 8 itself is still a way off from retail, and even much further away from internal IT adoption. The eight weeks until build is a pretty small amount of time to wait in comparison."

He added: "You all saw a very small technology demo of Windows 8, and a brief press release. We're all being quiet right now because we can't comment on this. It's not because we don't care, aren't listening, have given up, or are agreeing or disagreeing with you on something. All I can say for now is to please wait until September. If we say more before then, that will be great, but there are no promises (and I'm not aware of any plans) to say more right now. I'm very sorry that there's nothing else to share at the moment. I know that answer is terrible, but it's all that we can say right now. Seriously.

"This radio silence is a normal mode of operation for many companies 365 days of the year. Unfortunately, since we're so open with plans, since we share so much, and since we have such a solid history of helping and listening to our developer community, it's extra obvious when we're being quiet."

For good measure, he described his position: "[rock]Pete[hardPlace]".

That lack of clarity has upset some. Matt Baxter-Reynolds, director of AMX Software, told the Guardian: "In the past, Microsoft used to be clear about how they felt about developers. Developers knew that they were of critical importance to the company – including Ballmer's famous 'developers, developers' mantra-cum-outburst. Deprecating an entire platform as they did with Windows Phone 7 would have been unthinkable just five years ago.

"The company's clear lack of direction, which I believe is down to their lack of clarity as to just how to tackle Google and Apple is now bleeding into the messages that developers are getting. No one really knows if Silverlight is important going forward. Developers are having to assume that a fully fledged version of .NET will be available on ARM, but they might do something silly. No one knows if new tools are going to come down from the Visual Studio team to help build new these new, immersive Windows 8 apps. Perhaps more importantly, no one really knows if career decisions that tie a developer to the Microsoft stack will yield good salaries going forward.

"We all know that Bill Gates is not coming back to Microsoft, but at least because he was a developer and led the business in such a way that was friendly and supportive to developers we as developers did know that we were being looked after. This isn't the case under Ballmer. All that's happening is a fostering of fear, uncertainly and doubt."

Tim Anderson, an IT journalist with extensive experience writing about and with Microsoft's developer tools, observes that while .Net may not be under immediate threat "Windows has lost momentum to Apple in mobile, in tablets, and in high-end laptops, making Windows-only clients less attractive. In that context, the decision of the Windows team to favour HTML5 over .NET is a blow, in that it seems to concede that the future client is cross-platform, though I expect there will be some sort of outcry when we see all the proprietary hooks Microsoft has implemented to get HTML5 apps integrated into Windows 8. Therefore these really are difficult times for .NET. I do not count Microsoft out though; it still dominates business computing, and amongst consumers the Xbox may prove an important new platform."

Mary Jo Foley, who follows Microsoft closely, says that it is working on a WPF-like XAML layer for Windows 8 called "Jupiter". She noted: "Immersive apps are not meant to be Windows desktop apps. Nor are they necessarily pure web apps. They are applications that will be built using C#, visual basic (and maybe C++). These apps will be developed using the new Windows 8 app model and take advantage of its inherent servicing and packaging technologies and that will be available via the anticipated Windows 8 app store."

But others think the concerns are overblown. Manan Kakkar, an external developer, insisted that "the reason why we're having this discussion is because Steven Sinofsky did not mention Silverlight or WPF. Instead [he] said HTML5 and javascript will be the platforms of choice for the rich Windows 8 apps. To be clear, he was referring to the tablet interface. If only the pundits understood that Windows 8 will have two UIs, web crawlers would've had less crap to scan. Back to Silverlight, in my opinion this was Microsoft's way of telling the new college grads that using those snazzy new tools for HTML5 and JS you can still create apps for Windows."

However one developer commenting on his blog remarked that "the thing developers want to know is that you can create Silverlight for the *new* UI. Not for the desktop. There is utterly zero doubt that you'll be able to create out of browser Silverlight apps for the classic desktop UI."

Tim Acheson, who develops apps on Windows, told the Guardian: "I await clarification from MS before jumping to any conclusions. I think all developers including the .NET community buy into HTML5/JS/CSS and most will welcome this opportunity on Win8.

"The dev tools used by .NET devs already support HTML5, CSS3, etc very well indeed and these topics are always high on the agenda at official MS events. We're already building HTML5 apps. I've been doing so myself. IE9 supports HTML5 very nicely. It's reasonable to expect that we'll find that Silverlight runs on Win 8, at the very least in IE, and bear inmind that's essentially a compact .NET virtual machine. Even if development on Win 8 is radically different compared to previous versions, there's no great problem here, it's progress ... I can understand people's frustration, but really it's being triggered by uncertainty and the lack of detail, rather than the actual content of the recent presentation."

Even so, some developers are likely to keep pressing for more details up to Build – and, likely, beyond it.

If you're a Windows developer, we'd be interested to hear your views on Silverlight/WPF/HTML5-CSS-JS.