Amazon’s personal digital assistant (PDA) Alexa has been opened up to third party developers via an SDK, as Amazon begins to open up its voice-control ecosystem. Most familiar thanks to the Echo smart home device, Alexa will begin appearing in other hardware devices thanks to Amazon opening up the platform to developers – apparently free of charge. With Amazon Web Services powering the deployment, Alexa is a way for Amazon to inject itself into user’s lives – especially necessary after its Fire smartphone flopped spectacularly. With nearly all voice-based commands and queries made in mobile going to Apple’s Siri or Google Now, and a much smaller proportion secured by Microsoft’s Cortana, there’s a significant niche that Amazon can target using…