Jolla has released the software development kit installers for its forthcoming Sailfish OS, allowing developers to create apps on Linux, Windows and OS X.

Finnish mobile startup Jolla, formed by a handful of ex-Nokians, is on a mission to launch a Sailfish OS smartphone for the growing Chinese market. Based on the MeeGo and Mer operating systems, Sailfish was first publicly demoed at Helsinki's Slush conference late last year.

The company announced the SDK installer release on Twitter last week. Currently supported environments include Ubuntu 12.10, Fedora 18, Windows 7 Home and OS X 10.6, according to the release notes.

Jolla expects to ship its first Sailfish smartphones in the second half of the year, according to a recent tweet from its Jolla HQ account.

The startup's smartphone release date has been something of moveable feast: while Jolla has never firmly committed to a specific date, it was aiming to have a device ready by the end of 2012 . When Jolla showed off the Sailfish OS in a demo at Slush last November, staff said they expected the device to ship in the first half of 2013.

When the smartphone is finally ready to hit the shelves, Jolla has an agreement already in place with Chinese retailer D.Phone to distribute the device.

However, it will also be just one of many platforms vying for attention in an increasingly crowded mobile OS market behind iOS, Android, Windows Phone and BlackBerry.

Jolla announced its ecosystem - the Sailfish alliance - last October but its circle of supporters appears to be less developed than other platforms' that have debuted similarly recently.

Mozilla has released Firefox OS with carrier and ODM support, while Telefonica-sponsored Geeksphone has developer preview devices already in the hands of app makers. Similarly, Samsung has thrown its weight behind Tizen , which has an association backed by NTT Docomo, Sprint, SK Telecom, Huawei, Vodafone and Orange.

Canonical meanwhile has released the developer preview for Ubuntu Touch , while in China, where Jolla intends to make its mark first, local search giant Baidu is making headway with its Android-forked OS, low-cost smartphones from the likes of Dell and Lenovo.

And while At the Slush conference, Jolla did present a slide which showed China's Tencent logo on a slide, the only new partners it has officially confirmed are ST-Microelectronics and Finnish mobile network DNA.