John
Scallan.

Software Engineer — Full-Stack Development
React, Node.js, JavaScript, AWS
Building Scalable Systems at Lockheed Martin

John Scallan
Location Greater Philadelphia
Focus Full-Stack & Frontend
Education Penn State University
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01 — About

Building what
users touch.

Software Engineer with production experience across the full stack—from React and Angular frontends to Node.js and Express APIs to PostgreSQL databases and AWS cloud infrastructure. At Lockheed Martin, I ship code that serves users under real constraints: latency-sensitive APIs, high-throughput data pipelines, and mission-critical UI/UX.

I've been given the opportunity to architect and design systems that scale. I’ve cut API response times and optimized queries, automated large-scale data ingestion with AWS cloud tooling, and initiated an improvement of development and CI/CD workflows.

As a former Teaching Assistant for multiple courses at Penn State— University, I am able to communicate complex ideas clearly and elevate the engineers around me. Currently open to opportunities where I can solve hard problems, own meaningful features, and grow as an engineer.

Technical Stack

Primary
JavaScript TypeScript React Node.js Express PostgreSQL C++
Infrastructure
AWS Docker Kubernetes Helm CI/CD
Also Work With
Python Java Electron Git Agile

02 — Experience

Where I’ve built.

Software Engineer
Lockheed Martin Corporation
Apr 2026 — Present
King of Prussia, PA
  • Designed an event-driven data ingestion pipeline using AWS SNS, SQS, and Node.js, enabling reliable asynchronous communication and automated message processing across distributed services
  • Improved query performance ~10x by re-architecting a database schema from array-based ID storage to normalized junction tables, simplifying query logic and enforcing referential integrity
  • Implemented PostgreSQL row-level security policies using Knex-based query scoping to enforce permission-based data access within Express.js API routes from a React application, improving security and preventing data spills
  • Refactored database migration strategy to support backward-compatible migrations, eliminating the need for ad-hoc migration scripts, reducing database deployment overhead and cross-environment bugs
Software Engineer Associate
Lockheed Martin Corporation
Sep 2024 — Mar 2026
King of Prussia, PA
  • Optimized full-stack data flow between a React frontend and Node.js backend by reducing unnecessary API calls and restructuring endpoints for efficient large dataset handling
  • Refactored backend unit test infrastructure to use transactional database rollbacks instead of repeated migrations and seed operations, reducing test suite runtime from 45 minutes to 20 seconds (135x faster)
  • Automated data processing workflows using AWS Lambda and S3 and deployed containerized services on Kubernetes and Helm to support scalable batch data processing
  • Improved Docker-based development workflow by integrating a symlink-based hot-reload, eliminating unnecessary image rebuilds and accelerating local iteration speed
  • Developed React user interfaces using Material UI and custom CSS in a shared web and Electron-based desktop application, building reusable components and improving performance, usability, and responsiveness
  • Extended a C++ image processing pipeline with new capabilities, debugging segmentation faults and memory issues using gdb and cross-referencing the original MATLAB and Python implementations to validate correctness
  • Collaborated in an Agile environment with engineers, stakeholders, and customers to define requirements, deliver production features, and present solutions directly to end users
Software Engineering Intern
Lockheed Martin Corporation
May 2023 — Aug 2023
King of Prussia, PA
  • Developed full-stack features in an Angular web application enabling customers to manage contract workflows, and built backend services using Node.js and PostgreSQL to support APIs and core data models
  • Identified and resolved issues surfaced through CI/CD pipelines and automated test runs in development and staging environments, improving application stability during the development lifecycle
Engineering Intern
Federal Reserve Bank of Philadelphia
Jun 2022 — Aug 2022
Philadelphia, PA
  • Designed and implemented an internal scheduling system with Microsoft PowerApps and Power Fx, enhancing workflow efficiency for employees
  • Coordinated with internal stakeholders to design wireframes and define application requirements
  • Automated large-scale data updates with a PowerShell script, processing millions of employee records across servers in an SQL database

03 — Contact

Let’s connect.

Open to software engineering opportunities across industries. Let’s talk about what I can build for your team.

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