John Larkin

Staff Software Engineer

Brooklyn, NY

Work Experience

Staff Software Engineer @ MOJO
Aug 2025 – Present · NYC (Remote)
Python C++ Go Terraform
  • Led repricing solution for executed parlays for top client (8-figure deal)
  • Reduced pod memory usage by 5×, enabling migration from m-class to c-class instances
  • Increased FastAPI worker density, improving RPS per dollar
  • Oversaw team of 4 engineers on B2B initiatives
Senior Software Engineer @ MOJO
Apr 2024 – Aug 2025 · NYC (Remote)
Python C++ Go FastAPI
  • Designed FastAPI parlay pricing service with copula-based correlation pricing
  • Built high-performance C++ simulation aggregator for NFL/NBA models
  • End-to-end owner of EKS heartbeat sidecar service
  • Led tooling improvements: Poetry migration, Ruff/MyPy adoption, CI/CD standardization
Software Engineer @ Dropbox
Oct 2021 – Apr 2024 · SF, NYC (Remote)
Python TypeScript React Rust
  • Built Version Comparison and TLDW features using OpenAI transcription
  • Lead engineer for FSS Group Sharing and Replay quota counting
  • Led migration of 5M users to new sync engine
  • Mentored interns and delivered workshop to 55 incoming interns
Field Engineer @ Ab Initio
May 2019 – Oct 2021 · Chicago, IL
Python C# AWS SQL
  • Built high-volume, low-latency data processing systems
  • Won healthcare contract via optimized .NET ETL pipeline
  • Led Tanzu Kubernetes Grid cloud migration POC at multinational bank
Software Engineer @ Belvedere Trading
Aug 2017 – Apr 2019 · Chicago, IL
C# C++ Python React
  • Built reconciliation system between clearing and trading platforms
  • Implemented Greek visualization frontend
  • Helped build FIX execution gateway for OSE

Projects

Scrollz ACTIVE

Mobile app for managing newsletters with better search, note-taking, and social features. Includes web platform with automated email ingestion via Amazon SES.

Next.js Supabase OpenAI AWS

Tennis Scorigami ACTIVE

Data visualization exploring unscored tennis match combinations with 125k+ nodes, analyzing 750k+ sets across 57 years of tennis data.

Next.js React Neon Python

Walk in the Parquet ACTIVE

Lightweight desktop app for visualizing and querying Parquet files on macOS. Built with Tauri for native performance.

Tauri Rust DuckDB Next.js

Teaching a Computer How to Write

ML exploration teaching a computer to synthesize handwriting using attention mechanisms, LSTMs, and MDNs.

Python JAX LSTMs MDNs

Understanding Muon

Deep dive into the Muon optimizer with interactive visualizations and Karpathy's nanochat implementation.

Python Manim Pyodide

Quantum Ion Trap Visualizer

Interactive web app visualizing Paul trap physics for quantum computing education.

Vite React TypeScript

WordHunt Solver

AI-powered solver for iOS WordHunt using computer vision, OCR, and automation.

Python OpenCV Pytesseract OpenAI

GitHub PR Formatter

Chrome Extension that formats GitHub PR unfurls in Slack to show only titles for cleaner conversations.

JavaScript Chrome API

Volunteer & Leadership

Sierra Adventure Leader

Overland Summers · 2017

Led three 2-week adventure trips for 10-12 5th and 6th graders in the Tahoe and High Sierra area. Managed budgets, planned routes, and taught survival skills.

Senior Resident Assistant

Swarthmore College

Served as Senior RA, fostering community and supporting student wellbeing in residential life.

Tennis Team Captain

Swarthmore College · #1 Singles

Led the varsity tennis team as captain while competing as the #1 singles player.

City Hope Volunteer

San Francisco · 2022

Supported housing-insecure individuals in the Tenderloin neighborhood.

Programming Instructor

Chicago Boys & Girls Club · 2018-2019

Taught introductory programming concepts to children ages 9-14.

Tennis Coach

NFHS Accredited · Tennis on the Lake (Chicago)

NFHS accredited interscholastic coach. Coached youth tennis in Chicago.

Skills

Languages

Python TypeScript Go C++ C# Rust Swift SQL

Frameworks & Libraries

FastAPI React Next.js Tauri NumPy Pandas JAX

Infrastructure

AWS Kubernetes Docker Terraform PostgreSQL ScyllaDB

Domains

Distributed Systems Low Latency Trading Systems ML/AI Data Visualization

Education & Awards

Education

  • Swarthmore College — B.S. Engineering (Computer Engineering)
  • Minor in Chemistry
  • GPA: 3.82 (Major: 3.88)
  • Graduated May 2017

Awards & Honors

  • CoSIDA Academic All-District (2016)
  • Philadelphia Inquirer Academic All-Area (2016)
  • All-Centennial Conference First Team (2015, 2016)
  • Sigma Xi · Tau Beta Pi

Interests

🎾 Tennis

  • 4-year varsity (high school & college)
  • NFHS Accredited Coach
  • Tennis on the Lake Coach

🏔️ Mountains

  • Mt. Kilimanjaro (2013)
  • Mt. Rainier (2011)

🏊 Endurance

  • St. George 70.3 (2024)
  • Steelhead 70.3 (2023)
  • Indian Wells 70.3 (2021)
  • Chicago Marathon (2017)