Respected sir,
As per your requirement, you are looking for website developer for a website with GST calculator.
I have expertise in these kind of Web development.
I have Expertise in-:
Codeigniter, HMVC, Custom PHP, jquery, Ajax, Wordpress, HTML5, CSS3, JavaScript, Graphic Design, Website Design, Mysql database &bootstrap.
I will also provide these facilities after delivery-:
1. Maintenance & Services.
2. 6 month free support.
3. SEO friendly environment.
Thanks and regards.