freelancer for firebase firestore apps freelancer for supabase postgres apps freelancer for app refactoring and cleanup nextjs developer for hire freelancer for cross-browser testing mern stack development company hire full stack developer freelancer for pixel perfect development freelancer for ai powered web apps nextjs app development python web development https://thekingofjungle53189.madmouseblog.com/16930328/about-web-developer-online-courses-coursera