We designed the UI/UX and built CarbonTag's front-end in React, and structured the back-end on Supabase, integrating the company's proprietary emission-factor database. The platform turns carbon footprint calculation into a guided, multi-step form: the producer describes a product, its ingredients, origin, processing, packaging, transport, and storage, and gets back a full cradle-to-grave emissions analysis. Each product earns a CO2 Emission Score on a visual 1 to 6 scale, with a breakdown by type, by ingredient, and against other products, every number traceable to the scientific literature behind it. Around that, producers manage everything in one place: a "My Products" table with scores and CSV export, a dashboard with portfolio indicators, a Product Passes credit model, and multi-user accounts with dedicated support. Authentication, database, and APIs run on Supabase's scalable base, with documented code built for long-term maintenance.