App developers are withdrawing their products for sale from the US versions of Apple's App Store and Google's Android Market for fear of being sued by companies which own software patents - just as a Mumbai-based company has made a wide-ranging claim against Microsoft, Apple, Google, Yahoo and a number of other companies over Twitter-style feeds, for which it claims it has applied for a patent.

Software patent owners in the US have latched onto potential revenue streams to be earned from independent developers by suing over perceived infringements of their intellectual property - which can be expensive for developers to defend even if they are successful.

Now developers in Europe are retreating from the US to avoid the expense and concern such "patent trolls" are causing.

Simon Maddox, a UK developer, has removed all his apps from US app stores on both iOS and Android for fear of being sued by Lodsys, a company which has already sued a number of iOS and Android developers which it says infringe its software patent.

Shaun Austin, another app developer based in Cheltenham, said that "selling software in the US has already reached the non-viable tipping point".

And Fraser Speirs, a Scottish developer who has written apps for the Mac and iOS, remarked that he was "starting to get seriously concerned about my future as a software developer due to these patent issues".

The growth of patent lawsuits over apps raises serious issues for all the emerging smartphone platforms, because none of the principal companies involved - Apple, Google or Microsoft - can guarantee to protect developers from them. Even when the mobile OS developer has signed a patent licence - as Apple has with at least one company currently pursuing patent lawsuits - it is not clear that it has any legal standing to defend developers.

That has led developers to take evasive action. On Wednesday Maddox tweeted that he was removing his apps from US app stores and putting 0.575% of total revenue into a spare bank account. "Screw you, Lodsys", he commented.

He told the Guardian that it's "far too dangerous to do business" in the US because of the risk of software patent lawsuits.

But for US-based developers, the problems remain. Craig Hockenberry of Iconfactory, developer of Twitterrific, remarked that "Just when you think things couldn't get any worse, they do and tweeted that "I became an independent developer to control my own destiny. I no longer do". Iconfactory is among those being targeted by Lodsys, but earlier this week was granted a 30-day extension to reply to Lodsys's claim.

Meawhile Kootol Software of Mumbai announced that it has sent a notice to Microsoft, Apple, Yahoo, Google, IBM, Research in Motion, LinkedIn, MySpace, Research in Motion and a number of other companies - including Iconfactory - claiming that they infringe US patent application 11/995,343 - "A Method and System for Communication, Advertising, Searching, Sharing and Dynamically Providing a Journal Feed" - which it said has also been applied for in India, Canada and Europe.

It says that patent it is seeking is an invention which "allows the user to publish and send messages using one way or two way messaging and by subscribing to posts of other users of a network. By indexing each message of each user the system provides real time search capabilities to users of the network in turn creating a unique form of communication."

The company claims that it covers core messaging, publication and real-time searching, and that the named companies "may violate [our] intellectual property by using it for their website, networks, applications, services, platforms, operating systems and devices."

Because the patent has not apparently been granted by the US Patent Office or any other patent office, the warning message may give the companies involved the chance to contact the relevant examiners and have the claim invalidated because "prior art" - implementations which predate the application - already exist, notes Florian Mueller, who has followed the development of the field.

Mueller commented: "What surprises me is that the various patent offices examining this application haven't been able to reject it a while ago." This one is several years old. But now that many large players have been approached, chances are that this patent application will encounter some serious resistance. Let's hope it never gets granted in the first place."

Update: Mueller now says it is "too late to stop" the Kootol application becoming a patent in the US, with a strong presumption of validity in U.S. courts. A Scribd document has more details.



