Calvin DeBoer, Developer in Charlotte, NC, United States
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Calvin DeBoer

Verified Expert  in Engineering

Full-stack Developer

Charlotte, NC, United States
Toptal Member Since
January 31, 2020

Calvin is a talented full-stack engineer with more than a decade of experience building web applications with open-source tools. His strong technical skills and business experience give him the ability to communicate to and create alignment between developers, product owners, stakeholders, and executives.


Toptal Clients
Python, TypeScript, Azure, Cloud, Django, FastAPI, React Native, APIs...
Horizon Investments
Julia, ClojureScript, Python, APIs, REST APIs, Back-end, API Integration...




Preferred Environment

Slack, GitLab, Visual Studio Code (VS Code), Bash, Linux, MacOS

The most amazing...

...thing I've coded is an algorithm for fuzzy matching poorly constructed financial information to a highly structured schema.

Work Experience

Freelance Senior Software Engineer

2019 - PRESENT
Toptal Clients
  • Built a Python-based application that scrapes legal websites to gather court case updates and notifies followers of changes in dockets and other items. This application also gathers court filings for followers.
  • Enhanced a tax calculation and financial analysis SaaS project by adding user registration, payment, and calculation features.
  • Revitalized and transformed an old, legacy Node.js application, in the data-finance domain, into a well-tested Python-based application.
  • Performed security-focused application assessments and code reviews for various SaaS projects.
Technologies: Python, TypeScript, Azure, Cloud, Django, FastAPI, React Native, APIs, REST APIs, Back-end, Microsoft Excel, PostgreSQL, NumPy, Ansible, Sass, JavaScript, SQL, Project Management, Software Development, Software

Chief Technology Officer

2006 - PRESENT
Horizon Investments
  • Created and contributed to several open-source projects, primarily in the financial services domain.
  • Developed several full-stack web systems using a variety of tools and technologies. The nature of these systems is confidential.
  • Adapted software processes and communication protocols to changing requirements and growing teams.
  • Built a productive team environment for developing durable and maintainable code.
Technologies: Julia, ClojureScript, Python, APIs, REST APIs, Back-end, API Integration, Microsoft Excel, Software Development Management, Sockets, Telnet Protocol, Architecture, Project Leadership, Team Leadership, Data Modeling, Clojure, PostgreSQL, NumPy, Ansible, Sass, Reagent, Ruby, SQL, MATLAB, SciPy, Re-frame, CTO, Project Management, Software Development, Software

Iteround | Open Source Python Package
Iteround is an organic, standard, and sum-safe rounding library for Python. It solves a typical problem where elements are in an array-like structure that needs to be rounded while maintaining the rounded some of the original array. This is typical in representing percentages.

Custom B2B eCommerce Application

A Python and Django-based eCommerce catalog application with integrations to legacy inventory management systems, including SAP. This application also supported multiple languages and served a primarily B2B audience.

AI Web App | Security and Performance Improvements

A Python-based AI application. Initially, I was tasked with conducting a security review using OWASP Top 10 guidelines. Furthermore, I led efforts aimed at upgrading the authentication systems. Additionally, I guided a team of more junior engineers, assisting them through important refactors to enhance the system's performance.

Web Scraping Notification Tool | Lead Engineer

Acted as the sole developer building a Python-based web scraping application that investigates changes in the PACER court reporting system related to selected dockets and summarizes reports for the interested parties.


Python, Julia, Sass, Clojure, Bash, TypeScript, JavaScript, Ruby, Falcon, SQL, Python 3


Django REST Framework, Django, ClojureScript, Re-frame, React Native


REST APIs, NumPy, SciPy, Sockets, React, Django ORM


Microsoft Excel, Reagent, Ansible, GitLab, Slack, MATLAB, Git


Data Modeling, Project Leadership, Team Leadership, Architecture, APIs, Back-end, API Integration, CSV, Software Development Management, CTO, Software Development, Software, Project Estimation, FastAPI, Fintech, Cloud, Financial Services, Writing & Editing, Product Ownership, Security Analysis, Analytics, Sanic Web Server, SaaS, IT, Faceted Search, eCommerce, Search Engines, Search, Algorithms, Full-stack, Web Scraping, Telnet Protocol


Amazon Web Services (AWS), Mailgun, Azure, Linux, MacOS, Visual Studio Code (VS Code)


PostgreSQL, MySQL

Industry Expertise

Project Management


Functional Programming, REST

2004 - 2007

Bachelor's Degree in Finance and Economics

University of North Carolina at Charlotte - Charlotte, NC, USA