Kartik Agarwal, CEO of technosip.com believes technology landscape is dynamic, as a Startup company you are trying to solve a unique business problem. It's very important for you to be razor focused on you business problem at hand. At the same time, your success depends upon what technology stack you are using to solve your problem.Apple products use Objective-C, Android uses Java, there are engines which work for both but your mileage will vary. For website backends, you have a very wide choice of languages. For starters research Ruby on Rails (easy to get something up, but scales poorly), Python (easy, scales better, but less boilerplate is done for you), PHP (can be a royal pain to maintain), and Java (sometimes considered a heavy-handed solution, benefits/drawbacks controversial, the same language as Android but the benefit of having both be in the same language is extremely minimal). Each startup is unique and needs a unique set of technology stacks. You need someone who could help you stay relevant and it's time for to get onboard a consulting CTO.