Billie Heidelberg Jr.
Full Stack Engineer • Mobile Engineer
Full Stack Engineer • Mobile Engineer
I am a full stack engineer and mobile engineer with 8+ years building production web and mobile platforms. I have shipped iOS and Android contract work, founded a trading journal SaaS, and spent seven years at InvestCloud supporting 100+ developers on enterprise API integrations at scale. Across React, Next.js, TypeScript, Node.js, and PostgreSQL, I care about performance, reliability, and thoughtful user experience.
Alongside engineering, I have taught 150+ students through General Assembly's Web Development Immersive. Teaching rewired how I communicate — I explain complex ideas simply, support growing engineers, and collaborate naturally with product and design. I bring a craftsman's mindset to software: build things that are technically strong and genuinely helpful to the people who use them.
Today I am focused on full-time senior engineering work — a hands-on engineer who helps shape technical direction and ships impactful products at scale. If you want strong fundamentals, teaching experience, and a passion for building meaningful software, let's talk.
Work Experience
Full-Time Experience
Leading provider of digital financial services applications · Promoted through four roles over seven years
Key Achievements:
- Built and maintained ETL pipelines and internal automation tools using PostgreSQL, MySQL, Python, and Groovy, improving data processing efficiency by 25% and cutting integration setup time by 40%.
- Designed and implemented SOAP/RESTful APIs and relational database models supporting enterprise-scale financial applications for 50+ institutions.
- Debugged and resolved integration issues for 100+ developers globally, reducing resolution time through documentation and repeatable runbooks.
- Partnered with Engineering, QA, and Product teams to diagnose root causes of production data issues and verify fixes before rollout, cutting production incidents by 30%.
- Led technical training for the broader engineering org on debugging, integration patterns, and best practices, improving team efficiency by 30%.
- Contributed to schema design, API standards, and design-system consistency across the platform.
Major global advertising network known for award-winning campaigns.
Key Achievements:
- Developed interactive web components and digital advertising assets for major brand campaigns using HTML, CSS, and JavaScript.
- Collaborated with creative and UX teams to deliver responsive, pixel-perfect campaign pages.
- Implemented reusable components and animation sequences to reduce development time across concurrent campaigns.
Freelance & Client Work
Full-stack development for enterprise B2B intelligence platform
Key Achievements:
- Architected and delivered full-stack features for a SaaS platform serving enterprise clients, including user authentication, role-based permissions, and data management interfaces.
- Built responsive web applications using SvelteKit and TypeScript with a focus on type safety, maintainability, and scalable component architecture.
- Designed and implemented secure server-side APIs and database access layers with MySQL, ensuring data integrity and proper authorization controls.
- Participated in code reviews and contributed to engineering standards, improving code quality and team development practices.
Part-time through 2025; full-time (contract-to-contract) since January 2026
Key Achievements:
- Instructed 150+ students in full-stack development — React, Node.js, Express, MongoDB, Python, Django.
- Designed project-based curriculum and mentored students through portfolio projects, technical interviews, and career transitions.
- Assisted AI and Solutions Architect cohorts and led "Intro to AI Prompting" seminars.
Trading journal and analytics platform for active traders · Solo build
Key Achievements:
- Built a full-stack SaaS with Next.js 15, Supabase, and PostgreSQL, including 38+ row-level security policies and a normalized schema with triggers and stored procedures.
- Built a retrieval-augmented AI coach using OpenAI embeddings and pgvector, generating context-aware feedback grounded in each trader's own logged history.
- Developed interactive TradingView charts with real-time Polygon.io market data integration for session analysis and market replay.
- Deployed to Vercel with automated CI/CD and zero-downtime release processes.
Hair care discovery platform · React Native mobile app + React admin portal
Key Achievements:
- Built a cross-platform mobile app using React Native (Expo) with a Firebase backend, including Firestore, Auth, push notifications, and Cloud Storage.
- Developed a React admin portal integrating Algolia search with Firebase Cloud Functions for real-time product sync.
- Navigated the full iOS/Android App Store submission pipeline, including guideline compliance and push notification certification.
Short-term contract focused on modernizing Airbnb's host ambassador platform with measurable engagement and support improvements.
Key Achievements:
- Built and modernized frontend UI components for Airbnb's host management platform, improving the host onboarding and listing management experience.
Full-stack e-commerce platform with Next.js frontend and Django admin portal for luxury fashion brand.
Key Achievements:
- Built responsive dark-themed UI with interactive product displays.
- Implemented Django REST API for product management.
- Created custom admin portal for client inventory management.
Professional nonprofit landing page with community resources and mission-driven content.
Key Achievements:
- Designed responsive landing page with Next.js and Tailwind CSS.
- Created mission-driven content sections for community engagement.
- Implemented resource links and community initiative connections.
Startup Experience
Mobile content discovery platform for independent artists.
Key Achievements:
- Led end-to-end development of a React Native (Expo) app with a Supabase backend, including real-time subscriptions, role-based access, and media upload infrastructure.
- Designed a viral content ranking algorithm and improved feed performance by 40% through SWR caching.
- Directed sprint planning, code reviews, and iOS/Android release management via Expo Application Services.
Social discovery platform · 2,000+ active users
Key Achievements:
- Engineered scalable APIs and event-driven architecture using Apollo GraphQL, Hasura, and Node.js, including real-time notifications and async job workers.
- Built a global image caching pipeline using Sharp and S3, reducing bandwidth costs and improving load times by 40%.
- Integrated Twilio, Stripe, Mixpanel, and AWS SES for communications, payments, and analytics.
- Managed deployment and provisioning with Serverless Framework and Docker, automating migrations and reducing environment inconsistencies.