freelancer for supabase postgres apps react concurrent mode freelancer for responsive landing pages nextjs seo optimization freelancer for multi-tenant saas apps web design website design responsive web design freelancer for headless ecommerce sites react component-driven development freelancer for biometric time tracking zustand react state library web development firm react https://lukasejlll.tinyblogging.com/5-tips-about-software-developer-banner-for-linkedin-you-can-use-today-80134235