Software's to continue developing the website i would suggest that you use Bootstrap as front end development framework along with jquery which will give your site the ability to be responsive and scale to both a mobile and desktop and so you could have one website for both mobile and desktops , it would save you development costs and technical difficulties of maintaining 2 websites.
As the back end server side development environment i would suggest ASP.net (MVC) which offers easy and clean development and maintainability.
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Software's to continue developing the website i would suggest that you use Bootstrap as front end development framework along with jquery which will give your site the ability to be responsive and scale to both a mobile and desktop and so you could have one website for both mobile and desktops , it would save you development costs and technical difficulties of maintaining 2 websites.
As the back end server side development environment i would suggest ASP.net (MVC) which offers easy and clean development and maintainability.