Zaheer

Senior Software Engineer

Freelance Web Designer • Período integral

Sep 2021 - Present • 4 yrs 11 mos

Built 10+ production SaaS products from scratch covering fintech, payments, blockchain, and B2B platforms handling full product lifecycle from architecture to deployment. Built a full-stack ERP system for a Danish agency with 86 models, 33 services, 40+ API endpoints, Slack/Gmail/Meta/Google Ads integrations, and branded PDF export. Built and integrated APIs connecting 1,800+ European banks for an Open Banking platform, designing a unified abstraction layer across different bank API standards. Developed a blockchain crypto wallet handling 22K+ daily transactions with 99% success rate, reducing delivery time from 5-6 minutes to under 1 minute. Built merchant reporting software processing €21.3M monthly volume with automated reconciliation reducing manual effort by 50%. Designed ML-based fraud detection for a custom payment gateway, dynamically routing transactions based on card BIN, country, and transaction history. Led v2.0 rewrite of Fintech Back Office from monolith to modular architecture with instant mobile top-ups, remittance flows, and open banking APIs connecting 200+ banks. Built a 3-app AI IELTS platform solo (Node.js API + React admin + Next.js website) with 25 modules, 39 PostgreSQL tables, and Stripe subscriptions. Reviewed and QA'd Payfriend.io (Al invoice SaaS) identified and fixed 7 critical bugs in Stripe payment processing, FX calculations, and accounting sync. Developed multi-brand NFT marketplace API serving multiple reseller affiliates from a single codebase, processing 592K+ monthly transactions.