David Hartfield, Developer in Ann Arbor, MI, United States
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David Hartfield

Verified Expert  in Engineering

Software Developer

Ann Arbor, MI, United States
Toptal Member Since
March 4, 2020

David is a revenue-focused technical consultant located in Michigan. He helps translate clients' ideas into "tech talk" so they can launch as quickly as possible. He has experience working with a variety of organizations—all the way from one-man startups to Fortune 500 companies. He loves seeing the potential of his projects to add profits, bump up scalability, or cut costs.


Apollo, GraphQL, TypeScript, Next.js, React
Amazon API Gateway, AWS Lambda, Amazon Elastic Container Service (Amazon ECS)...
Social News Desk
React, Node.js, Swift, Objective-C, Java, React Native




Preferred Environment

Atlassian Suite, Atlassian, Postman, Adobe Photoshop, Sonar, IntelliJ, WebStorm, Docker

The most amazing...

...tool for mobile app development is React Native—I love using this technology and saving time by re-using 85% of the code base between mobile apps.

Work Experience


2019 - 2021
  • Led the development of the hilton.com homepage that serves millions of users daily and the brand refresh and redesign. The rearchitected web app was built on React and Next.js, backed by an Apollo GraphQL API.
  • Built shared atomic components shared by multiple React and React Native applications, following company-wide standardized design standards and best practices.
  • Engineered a highly-customizable component management system allowing Content.
  • Built editors to manage, preview, and deploy web content outside of SDLC by integrating with Bloomreach channel manager and Hippo CMS.
  • Integrated public applications with third-party APIs, including TripAdvisor, Foursquare, and Google Maps.
  • Ensured Level A success criteria for the Web Content Accessibility Guidelines (WCAG).
Technologies: Apollo, GraphQL, TypeScript, Next.js, React

Software Architect

2014 - 2019
  • Led an agile team of six remote US-based developers in building the core product of the company. The main project consisted of a scalable Java/Spring/Docker cloud-based web API and Angular front end that used Canvas/CreateJS to game development.
  • Modernized the company’s monolithic single-tenant application to a high availability multi-tenant SaaS microservice architecture to allow the company to scale to millions of users with high performance.
  • Migrated Java/Spring services to Docker containers on an AWS ECS infrastructure behind AWS API Gateway—all managed and configured through AWS CloudFormation.
  • Optimized memory footprint and resource usage of Java/Spring applications by adopting Spring Batch for large batch processing of data, AWS ElastiCache for distributed caching, and AWS Aurora for distributed multi-tenant data persistence.
  • Hired and trained new developers in establishing coding standards and best practices while providing mentorship.
  • Architected HIPAA-compliant solutions to pass HIPAA audits.
Technologies: Amazon API Gateway, AWS Lambda, Amazon Elastic Container Service (Amazon ECS), Angular, Spring, Java

Lead Mobile App Developer

2016 - 2018
Social News Desk
  • Led the development of iOS and Android apps for rapid deployment to both the iTunes Store and Google Play Store.
  • Developed apps in React Native to reuse ~85% code between platforms and harness Java and Objective-C where necessary.
  • Spearheaded mobile development while coordinating changes with the API development team and working with designers and testers to rapidly prepare apps for regular production deployments.
  • Solved implementations problems by engineering new React Native libraries and collaborating with stakeholders and designers to architect the best user experience.
Technologies: React, Node.js, Swift, Objective-C, Java, React Native

Social Media Management App

The app is used for managing several social media accounts across multiple platforms (Facebook, Twitter, Instagram). I led the development of the (React Native) mobile application for both iOS and Android and on a phone and tablet. We integrated with custom third-party SSO implementations and built out a custom chat feature.


JavaScript, Java, TypeScript, Objective-C, Swift, PHP, GraphQL


React Native, Next.js, Redux, A-Frame, Angular, Spring


REST APIs, React, Node.js, Facebook API, Google Maps API


Git, Construct 2, AWS CloudFormation, Sketch, Maya, WebStorm, IntelliJ, Sonar, Adobe Photoshop, Postman, Atlassian, Atlassian Suite, Amazon Elastic Container Service (Amazon ECS)


AWS Lambda, Amazon Alexa, Docker, Amazon Web Services (AWS), Firebase


HIPAA Compliance


MongoDB, PostgreSQL


WebSockets, Serverless, Amazon API Gateway, Apollo, Chemistry

2003 - 2007

Bachelor's Degree in Chemistry

Michigan State University - East Lansing, MI