sudder

The server software is available here: http://strezhi.ru/temp/2015/websdr-dist11.tgz

Binary only, but not obfuscated or anything like that, so reverse engineering it isn't too onerous.

The software for those WebSDRs can be found at http://strezhi.ru/temp/2015/websdr-dist11.tgz, might be an interesting project to add such features to it.

Though there is also OpenWebRX at http://sdr.hu/openwebrx, which does essentially the same thing but is more open source. It has some decoder plugins already.