Generally, the cost to build a simple HTML website may go up to $1,000-$5,000. And the cost to build a basic mobile app backed with HTML5 and other technologies can vary from $10,000-$100,000. However, there is no certain figure since it totally depends on website features and business scope. If you want to know the exact value of your HTML5 web or mobile app development project then we advise you to share your requirements and then we can give you an estimation.