Mihail
Griniuc.

Apr 2025 — Present

Full Stack Software Engineer

Koopel

New York, NY

Current role

80%

lower user drop-off

• Built and deployed a full-stack peer-to-peer marketplace serving 1000+ users and processing 1000+ listings across the U.S.
• Shipped the platform end-to-end — frontend, backend, APIs — plus a cross-platform iOS/Android app.
• Designed core marketplace systems: listings, search, messaging, transactions, escrow payments, verification, anti-fraud.
• Reduced user drop-off by 80% and improved page load performance by 70% through UX and performance tuning.

React · React Native · Next.js · Node.js · PostgreSQL · AWS · LLM APIs

May 2023 — Feb 2025

Software Engineer

Proficon Services LLC

New York, NY

75%

shorter billing cycles

• Built an AI-powered B2B invoicing system that cut billing cycle time by 75% and minimized manual errors.
• Automated invoice validation, approval workflows, and PDF generation, eliminating billing bottlenecks.
• Integrated services with internal accounting systems via REST APIs for real-time financial reporting.
• Applied LLM text understanding to convert unstructured client inputs into structured invoice line items.

Node.js · PostgreSQL · Supabase · REST APIs · LLM APIs

Feb 2021 — Feb 2023

Software Engineer

YRB Club LLC

New York, NY

35%

improvement in order accuracy

• Built internal tools that streamlined operations and improved system reliability.
• Improved order fulfillment accuracy by 35% via automated database sync jobs and validation scripts.
• Led a small engineering team; improved delivery velocity through task breakdown and documentation.
• Boosted customer retention by 20% through behavioral data analysis and targeted improvements.

Node.js · PostgreSQL · AWS