6+ years shipping production software end-to-end across mobile, web, and backend. Senior Engineer at Input Output (IOHK); previously a founding engineer scaling a FinTech app to 100K+ users at Bolster, and co-founder of a crypto-education startup. I build full products solo, with LLMs, RAG, and Claude Code as a force multiplier.

Production systems that use LLMs, RAG, and vision to do real work — not demos.

Settle — AI bill review for waste haulers · Claude Vision + human-in-the-loop
Flags hidden markups in fuel/tipping invoices, gated by an approval queue. · Live demo →
Next.js · TypeScript · Claude · Neon · Drizzle

Hiring Radar — autonomous matching agent + long-term memory · hybrid semantic + full-text search
recall@10 0.52 vs 0.28 semantic-only (pgvector HNSW + RRF) — Inngest pipeline, MCP server. · Live demo →
Next.js · TypeScript · pgvector · MCP · Neon

Shoebox — 100% on-device receipt digitizer · OCR + fine-tuned local model
~90% of cloud-vision accuracy at $0, fully offline — QLoRA fine-tune (80% vs 72% base), published to HF Hub. · HF model →
Python · PaddleOCR · Ollama · MLX · scikit-learn

Rubric — CI for prompts · golden sets + LLM-as-judge with calibration
Fails the PR when a prompt or agent change makes the output worse — judge calibrated to Cohen's κ 0.81. · Live demo →
TypeScript · Next.js · Turso · Groq · GitHub Actions

Daily News — full-stack news app with an Ask AI feature
Answers grounded in the articles with tappable citations (RAG) — local embeddings + Groq via a Cloud Function. Clean Architecture + BLoC, rules tested in CI.
Flutter · Dart · Firebase · RAG

• nicomastakas.com — this portfolio site, notable for a from-scratch cookieless, first-party analytics system (own collector → Neon → private dashboard), no third-party tracker. Live → · Next.js · TypeScript · MDX · Neon
• TodayOnly — a daily task manager that only manages today. Native SwiftUI + SwiftData (macOS) and Tauri/Rust (Windows). My own product.
• Tether WDK Wallet — non-custodial mobile wallet on the Tether WDK. Biometric unlock, Secure-Enclave key storage, multi-asset. React Native
• Tic Tac Toe — mobile-first game with an AI opponent, a custom design system, and an Infinity mode. iOS / Android / Web. Expo

• Spotify Genre Sorter — Python CLI that auto-sorts Liked Songs into genre/vibe playlists, dry-run preview + multi-membership bucketing. Python
• ProductSequenceAPI — REST API for product-ID subsequences. Node.js · Express · MongoDB · Docker · JWT · Jest

Smaller apps, clones and learning exercises live across my other repositories.