1) I designed and developed an e-commerce backend similar to Mercado Libre using NodeJS and MongoDB. 2) I designed and developed a backend for a loan system similar to a conventional banking system. 3) I designed and developed a backend for a proxy system and real-time data processing for Stripe, Hubspot, and other platforms. 4) I collaborated in the development of blogs and websites using WordPress with fellow colleagues during my freelance career. 5) I managed VPS and dedicated servers for application deployment. 6) I designed and developed an invoicing system for a candy distribution company.