Finalize ScanMyPetNow Platform

ScanMyPetNow is already live on Netlify, written in vanilla HTML, CSS and JavaScript with Netlify Functions driving the serverless backend. I now need the last pieces put in place so the service can accept real users and payments and move confidently into production... (Budget: $250 - $750 USD, Jobs: API Development, Backend Development, CSS, Database Development, HTML, JavaScript, Netlify, Payment Processing, PHP, Testing / QA)