John McConnell
Verified Expert in Engineering
Software Developer
San Jose, CA, United States
Toptal member since March 16, 2022
John is a professional developer whose duty is to understand his client's unique needs and make them a reality. The different hats he wore to help his team thrive include solo developer, team mentor, project manager, product manager, and CTO. He developed a network forecasting and allocation pipeline, sports party game, SAT education platform, resource management system for deployed assets, social networking application with content feeds, real-time chat, and dynamic content subscriptions.
Portfolio
Experience
- SQL - 9 years
- Go - 8 years
- Java - 8 years
- System Design - 7 years
- Clojure - 7 years
- User Experience (UX) - 5 years
- Ruby on Rails 5 - 5 years
- Flutter - 4 years
Preferred Environment
Clojure, Flutter, Go, Java, gRPC, React, Machine Learning, Google Cloud, Amazon Web Services (AWS), Architecture
The most amazing...
...product I've developed is a sports party mobile game. I designed and grew the application to 300 DAU over seven days and 100 DAU over one day.
Work Experience
CTO
StripCard
- Grew the product to 300 DAU over seven days and 100 DAU over one day. Deployed the mobile application, customer splash page, and back-end services.
- Prioritized features and deliverables and reviewed feedback from customers.
- Negotiated scope, vision, and direction with my cofounder.
Java Engineer
Coupang - Rocket Growth
- Designed and implemented a real-time pricing system for CPI calculations impacting 10+ million customers, improving responsiveness and accuracy of marketplace pricing.
- Developed and maintained distributed systems leveraging AWS EC2, Kafka, and DynamoDB to handle high-scale data synchronization and message processing.
- Built and deployed a web crawling pipeline for business intelligence, enabling data-driven insights for competitive pricing and product analysis.
Senior Clojure/Clojurescript Engineer
OnChain Studios, Inc
- Developed a migration strategy and mentored the fellow engineering team for the legacy Clojure/ClojureScript code base.
- Developed a chat based ML pipeline and infrastructure for a greenfield project.
- Made many last-minute business critical changes to the production code in preparation for business demand (catalog changes, purchasing flow, and notifications).
Solution Architect
Animo Services LLC
- Led a team of developers to build the credit card product. We gained over 400 credit card users in the first week of launch with an average rating of 4.5 out of 5.
- Managed the team processes and negotiated product scope and deliverables for each sprint.
- Led the design and architecture of both the front end and back end of the credit card product. The system handled the scale of the launch, and we delivered the product on time and exceeded stakeholder expectations.
Senior Engineer
- Implemented a forecasting simulation for a large network migration to inform decisions for the next quarter's network deployment.
- Worked on a team to design and implement forecasting methodologies for Google's global network. I completed multiple mission-critical experiments ahead of schedule and numerous last-minute changes to the design.
- Discovered a heavily hit performance hotspot of our user-facing dashboards. I proposed and implemented a solution and added regression criteria to our testing suite, decreasing from 15 seconds to 200 milliseconds the latency of our dashboards.
Senior Engineer
Apple
- Pioneered a Spark application utilizing the employee directory to decrease indexing the authentication ACLs from 24 hours to 20 minutes using the new Spark pipeline.
- Developed a GDPR compliance application for next quarter's auditing report. I worked cross-functionally with the product team to complete the resource management system in a timely manner.
- Built a caching system for our resource ETL pipeline. It reduced outages from one per week to no outages since its implementation.
Software Engineer
Enova International
- Designed and developed a discrete event simulation engine to process and manage the lifecycle of a loan in time for the next quarter's financial statements.
- Built and executed numerous UI and back-end changes under tight deadlines.
- Proposed and implemented alternative strategies for improving the codebase and team processes.
Experience
StripCard App
I act as the CTO and lead the product's implementation and design.
Education
Master's Degree in Computer Science
University of Illinois - Champaign, IL
Skills
Libraries/APIs
REST APIs, Stripe, React, WebRTC, Node.js
Tools
Git, Jenkins, Autotask, RabbitMQ
Languages
Clojure, Go, Java, JavaScript, Python, SQL, HTML, Elixir, CSS, C++, Kotlin, Swift, GraphQL, Snowflake
Frameworks
Flutter, Spring Boot, Ruby on Rails 5, gRPC, Django, Ruby on Rails (RoR), React Native, Spring, ClojureScript, Ruby on Rails 4, Spring 6
Paradigms
Microservices, ETL, Object-oriented Programming (OOP), Continuous Integration (CI), Mobile Development
Platforms
Twilio, Amazon Web Services (AWS), Apache Kafka, Kubernetes, Firebase, Oracle, Azure
Storage
PostgreSQL, JSON, Google Cloud, Data Integration, MySQL, Elasticsearch, Google Cloud Datastore, Amazon S3 (AWS S3), Amazon DynamoDB
Industry Expertise
Project Management
Other
Resource Management, Software Design, APIs, System Architecture, Full-stack, Web Development, Architecture, Software Architecture, Data Extraction, System Design, User Experience (UX), Minimum Viable Product (MVP), Data Architecture, Software Development Management, Solution Architecture, OpenAI GPT-3 API, Scripting, Technical Leadership, CI/CD Pipelines, Machine Learning, Operating Systems, Data Mining, Statistics, Product Design, Video Streaming, Audio Streaming, Team Management, Cloud, Data Scraping, Distributed Systems
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