Hello, my name is Thomas Callen and I'm a
I specialize in building high-quality web applications using modern technologies like React, Next.js, and TypeScript. With a strong foundation in computer science and a passion for coding, I create efficient and scalable solutions that meet user needs.
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!
Back-end Development
FastAPI / Node.js / Express / Next.js / SQL
Front-end Development
React / Next.js / Tailwind CSS / JavaScript
Embedded Systems Prototyping
Arduino / Raspberry Pi / C / C++
2025
Mobile App Development, Backend Development, AI, Document Parsing
A voice-driven report-filling tool: import empty reports (TXT/DOCX/PDF) from the device, convert them to a machine-readable template on a FastAPI backend, and use live speech to populate comment sections in a React Native (Expo) app with tab navigation.
Frameworks: React Native, Expo Router, FastAPI
Languages: TypeScript, Python
Libraries: expo-speech, expo-document-picker, expo-file-system, react-native-safe-area-context, pydantic, uvicorn
2025
Algorithmic Trading, Machine Learning, Web Development
Python engine that backtests multiple k-means–style centroid counts to discover the highest-performing unsupervised stock-selection strategies among the most liquid tickers each month. The top strategy selects positions at each month’s start and automatically places orders via the Alpaca Trading & Broker API. A companion Next.js dashboard visualizes recent trades, current portfolio value, and historical performance.
Frameworks: Next.js, FastAPI
Languages: Python, TypeScript
Libraries: pandas, numpy, yfinance, alpaca-trade-api, scikit-learn
2024
Internet of Things (IoT), Embedded Systems, Cloud Databases, Web Development
Multipart project for GLBL Foundation: assembled Raspberry Pi Pico–based sensor nodes integrating turbidity, total dissolved solids (TDS), and temperature sensors; transmitted telemetry to Azure IoT Hub (Microsoft IoT Hub); and stored/query datasets in Azure SQL Database (Microsoft SQL Server–compatible). In parallel, helped build a Next.js/React website to communicate the foundation’s mission and lay groundwork for future data visualization of device readings.
Framework: Next.js
Languages: MicroPython, Python, TypeScript, SQL
Libraries: React, azure-iot-device, pyodbc