freelancer for firebase firestore apps freelancer for app refactoring and cleanup freelancer for cross-browser testing freelancer for multi-tenant saas apps freelancer for admin dashboard ui react wasm integration responsive web design react micro-frontends react component-driven development react recoil state management freelancer for ai powered web apps nextjs app development https://trevorpgbwm.full-design.com/software-developer-kerja-apa-no-further-a-mystery-78713760