Marshall Shen, Developer in Chicago, IL, United States
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Marshall Shen

Verified Expert  in Engineering

Full-stack Developer

Location
Chicago, IL, United States
Toptal Member Since
September 13, 2022

Marshall is an accomplished technical leader with a strong background in building AI software and leading engineering teams. He has delivered innovative solutions for tech companies of all sizes in fintech and healthcare. With over three years of experience running startups, he has led engineering teams of over 20 people, including offshore teams in China. As a software architect at Venmo, he builds scalable payment systems, mentors engineers, and builds a resilient engineering organization.

Portfolio

Venmo
Python 3, Docker, Java, Ruby, Django, Technical Leadership, React...
One Step Holdings LLC
Amazon Web Services (AWS), Technical Project Management...
Therapy App LLC
Java, Spring Boot, PHP, Amazon Web Services (AWS), Laravel, React, Vue...

Experience

Availability

Part-time

Preferred Environment

MacOS

The most amazing...

...app I've built is Venmo, extending it with consumer financial products such as credit and debit card.

Work Experience

Senior Staff Software Engineer

2019 - PRESENT
Venmo
  • Developed a credit card product that scaled to more than 500,000 active users, with over $1 billion annual transaction processing volume.
  • Migrated a monolithic Python Django application into a microservices architecture, with a React web front-end, MySQL and DynamoDB as data storage, and Kafka as data streaming.
  • Functioned with technical leadership, overseeing and mentoring over 40 software engineers within the organization.
Technologies: Python 3, Docker, Java, Ruby, Django, Technical Leadership, React, API Architecture, Fintech, MySQL, Bash, TypeScript, Amazon RDS, Software Development, Algorithms, MongoDB, HTML, JavaScript, Python, Ruby on Rails (RoR), Kubernetes, Test-driven Development (TDD), APIs, Google Cloud, Firebase, Cloud Firestore, Back-end, Amazon Web Services (AWS), Back-end Development, Git, Amazon EKS, Web Development, REST APIs, Spring, Spring Boot, Unit Testing, Integration Testing, Software Testing Automation Framework (STAF), Material UI, User Interface (UI), MUI CSS, CSS, Node.js, GraphQL, OpenAPI, Full-stack, Linux, ESLint, Enterprise, Enterprise Systems, Software Architecture, Team Leadership, Jira, Project Management, Slack, GitFlow, Agile Project Management, Architecture

AWS Architect

2022 - 2023
One Step Holdings LLC
  • Consulted with clients to determine their business needs.
  • Developed software designs using AWS to meet those needs.
  • Created a Python/Docker codebase that lets clients quickly begin product development.
Technologies: Amazon Web Services (AWS), Technical Project Management, AWS Certified Developer, Agile Project Management, Project Management

Senior Developer

2022 - 2023
Therapy App LLC
  • Built expert HIPAA-compliant data pipelines for personal patient data.
  • Served 40+ mental health clinics across the US, providing practical solutions tailored to each client's needs.
  • Delivered requested patient information within tight timelines without sacrificing quality.
Technologies: Java, Spring Boot, PHP, Amazon Web Services (AWS), Laravel, React, Vue, React Native, MongoDB

Staff Software Engineer

2018 - 2019
Braintree
  • Built a payment processing solution for enterprise merchants like Uber and Airbnb and handled a daily processing volume of over $10 billion using Ruby on Rails, Postgres DB, and Kafka stream.
  • Created banking integration with National Australian Bank to launch payment processing service across all Braintree merchants in Australia.
  • Oversaw a financial audit process to ensure the financial ledger met compliance requirements.
Technologies: Ruby, Ruby on Rails API, Java, Terraform, PostgreSQL, API Architecture, Technical Leadership, Software Development, QuickBooks API, Algorithms, HTML, Angular, JavaScript, Python, Ruby on Rails (RoR), Kubernetes, RabbitMQ, Test-driven Development (TDD), APIs, Back-end, Amazon Web Services (AWS), Back-end Development, Git, Web Development, REST APIs, Spring, Spring Boot, Unit Testing, Integration Testing, Software Testing Automation Framework (STAF), User Interface (UI), CSS, Bootstrap, Node.js, OpenAPI, Full-stack, Linux, Enterprise, Enterprise Systems, Software Architecture, Team Leadership, Jira, Project Management, Slack, GitFlow, Agile Project Management, Architecture

Senior Software Engineer

2015 - 2017
PatientPoint
  • Launched a new product that managed digital content across 10,000+ IoT devices. Used Ruby on Rails for the back end, Vue.js for the front end, and Postgres DB as data storage.
  • Acted as a tech lead for a team of ten developers and prioritized development tasks with the product and leadership team.
  • Designed RESTful APIs and relational database systems for healthcare content streaming from scratch.
Technologies: Ruby, Vue, Ruby on Rails API, Technical Leadership, PostgreSQL, Software Development, Algorithms, HTML, JavaScript, Chrome Extensions, Ruby on Rails (RoR), Test-driven Development (TDD), APIs, Back-end, Amazon Web Services (AWS), Back-end Development, Git, Heroku, Web Development, REST APIs, Unit Testing, Integration Testing, Software Testing Automation Framework (STAF), User Interface (UI), CSS, OpenAPI, Full-stack, Linux, Enterprise, Enterprise Systems, Software Architecture, Jira, Project Management, Slack, GitFlow, Agile Project Management

Software Engineer

2012 - 2015
Groupon
  • Launched an internal accounting service to help merchant payments and developed payment algorithms that processed more than 1 billion USD of payments.
  • Developed and maintained the Ruby on Rails app with more than 100,000 merchants globally.
  • Worked with the Groupon finance and accounting team to help process and reconcile payments.
Technologies: API Architecture, Amazon Web Services (AWS), Computer Security, Software Development, QuickBooks API, Algorithms, HTML, JavaScript, Ruby on Rails (RoR), Test-driven Development (TDD), APIs, Back-end, Back-end Development, Git, Heroku, Web Development, Java, REST APIs, Spring, Spring Boot, Unit Testing, Integration Testing, Software Testing Automation Framework (STAF), User Interface (UI), CSS, OpenAPI, Full-stack, Linux, Enterprise, Enterprise Systems, Software Architecture, Jira, Project Management, GitFlow, Agile Project Management

Venmo Credit Card

https://venmo.com/about/creditcard/
The Venmo Credit Card allows users to earn custom cash back to send, spend, or auto-purchase the crypto of their choice from their Venmo account.

I was a tech lead for this project, leading the high-level architectural design and guiding 40+ software engineers.

HackerPen

HackerPen is an interactive, online peer-to-peer mock interview platform that allows people to practice technical interviews with each other using video or audio chat and collaborative coding and drawing pads, all in one web app.

I created this platform and launched it in April 2022. As of September 2022, the platform is running with 300+ active users.

Maestro

A mobile app that helps people practice sight-reading music.

The technology used: React Native, AWS Lambda, with RESTful APIs.

The app achieved over 2,000 downloads during the first six months of launch on iOS and the Google app store.

BuildU

A student engagement application focused on American universities and colleges. The system was built on Ruby on Rails, React and React Native.

I worked as the CTO of the company, and I was in charge of building the application and managing the software development process.

Kana - Learn Japanese

A mobile app that teaches people Japanese. The app was released on the iOS app store in 2019, and it teaches people Hiragana through flashcards and pop quizzes. The app had more than 1,000 downloads, although it's no longer under maintenance.
2014 - 2015

Master's Degree in Computer Science

Columbia University - New York, NY, USA

2008 - 2012

Bachelor's Degree in Statistics

University of Iowa - Iowa City, IA, USA

2008 - 2012

Bachelor's Degree in Computer Science

University of Iowa - Iowa City, IA, USA

JULY 2020 - PRESENT

Functional Programming Principles in Scala

Coursera

APRIL 2019 - PRESENT

Deep Learning Specialization

Coursera

OCTOBER 2017 - PRESENT

Interaction Design Specialization

Coursera

Libraries/APIs

Ruby on Rails API, React, REST APIs, Node.js, OpenAPI, Vue, QuickBooks API

Tools

Git, Jira, Slack, Terraform, Google Compute Engine (GCE), Amazon EKS, RabbitMQ, Cron

Frameworks

Django, Ruby on Rails (RoR), Spring, Spring Boot, Material UI, MUI CSS, Bootstrap, Flutter, React Native, Angular, Laravel

Languages

Python 3, Java, Ruby, Bash, TypeScript, HTML, JavaScript, Python, CSS, Elixir, PHP, GraphQL, Scala, SQL

Paradigms

API Architecture, Test-driven Development (TDD), Unit Testing, Agile Project Management

Platforms

Docker, MacOS, Amazon Web Services (AWS), Linux, Google Cloud Platform (GCP), Kubernetes, Firebase, Heroku

Storage

MySQL, PostgreSQL, MongoDB, Google Cloud, Cloud Firestore, Databases, JSON, Company Databases

Industry Expertise

Project Management

Other

Software System Architecture Development, Technical Leadership, Software Development, Algorithms, APIs, Back-end, Back-end Development, Web Development, Integration Testing, Software Testing Automation Framework (STAF), User Interface (UI), Full-stack, ESLint, Enterprise, Enterprise Systems, Software Architecture, GitFlow, Architecture, Computer Science, Amazon RDS, Technical Program Management, Chrome Extensions, Team Leadership, Artificial Intelligence (AI), Computer Security, Statistical Analysis, Statistical Modeling, Interaction Design (IxD), Fintech, CTO, Technical Project Management, AWS Certified Developer, CSV

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