Hello, my name is Thomas Callen and I'm a

Software Developer.

I build end-to-end software, from modern web apps to the backend systems and infrastructure that support them. With a strong computer science background, I focus on writing clean, scalable code that solves real problems.


Feel free to explore my portfolio to see some of the projects I've worked on, and don't hesitate to reach out if you'd like to connect or collaborate!

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Backend Development

Back-end Development

FastAPI / Node.js / Express / Next.js / SQL

Frontend Development

Front-end Development

React / Next.js / Tailwind CSS / JavaScript

Embedded Development

Embedded Systems Prototyping

Arduino / Raspberry Pi / C / C++

Work I'm Working On:

Single-Player Texas Hold’em Poker cover photo

2025

Single-Player Texas Hold’em Poker

Game DevelopmentFrontend Development

A browser-based single-player Texas Hold’em poker game built with a deterministic TypeScript game engine and a React UI. The project uses an event-driven reducer to model game flow, declarative side effects for bot turns and delayed transitions, and isolated hand evaluation logic. Designed with a strong separation between domain logic and presentation, the engine is fully testable and independent of the UI.

Frameworks: React, Vite

Languages: TypeScript, HTML, CSS

Platform: AWS Amplify

Prediction Royale cover photo

2026

Prediction Royale

FintechData AggregationFull-Stack DevelopmentMarket Analysis

A real-time prediction market aggregator that continuously ingests and cross-matches events from Kalshi and Polymarket. A Go-based matching engine scores event pairs by title similarity, outcome labels, category tags, and close time — then precomputes probability divergences and liquidity metrics across all matched outcomes. The Next.js web app surfaces the most liquid, most divergent, and soonest-closing pairs through a dark fintech interface featuring a hero carousel, tag-based market browsing, per-market mirrored outcome bars, and a live search autocomplete.

Framework: Next.js (App Router)

Languages: TypeScript, Go, SQL

Librarys: Tailwind CSS v4, postgres.js, pgx/v5

Platforms: PostgreSQL, Kalshi API, Polymarket API