James Koshigoe, Developer in San Francisco, CA, United States
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James Koshigoe

Verified Expert  in Engineering

Software Developer

San Francisco, CA, United States
Toptal Member Since
April 2, 2014

James is a software engineer and consultant focused on web development. He has over a decade of experience in both startup and enterprise business environments building solutions where full-stack skills, creative thinking, and high attention to detail are key, and fast turnaround is paramount.


Web Performance Optimization (WPO), Website Performance, CSS, Django, Python 3...
CSS, Subversion (SVN), Git, MySQL, Ext JS, Node.js, JavaScript, PHPUnit...
InvitedHome (formerly Vacation Rental Partner)
Ruby, JavaScript, CSS, Git, jQuery, RSpec, PostgreSQL, CakePHP, PHP...




Preferred Environment

Linux, MacOS, Git, Vim Text Editor, IntelliJ IDEA

The most amazing...

...system I've ever built is an enterprise permission system providing security to every instance of data while maintaining scalability.

Work Experience

Full-Stack Software Engineer Consultant

2014 - PRESENT
  • Architected and led a development team building a Spotify-like application for a Series-A funded startup using Node.js, Electron, and React.
  • Worked full-stack on the team to develop a consumer-facing review platform with Node.js, React, GraphQL, Elasticsearch, and PostgreSQL.
  • Built optimization algorithms to automate advertising campaign management using Facebook's Marketing API, Python, Django, and PostgreSQL.
  • Built a bidirectional shipping integration API with Ruby on Rails for a very large affiliate network corporation.
  • Managed multiple overseas engineering teams using Agile practices.
Technologies: Web Performance Optimization (WPO), Website Performance, CSS, Django, Python 3, Ruby on Rails (RoR), Node.js, React, TypeScript, JavaScript

Senior Software Engineer

2013 - 2014
  • Automated and optimized as much of IMM's manual processes as possible so IMM's talent could focus on what they do best.
  • Provided technology and architectural experience to build core infrastructures upon which other developers relied.
  • Built high-traffic websites for IMM's digital marketing campaigns for well-known brands such as TracFone, Chili's, On The Border, DirectBuy, and more.
Technologies: CSS, Subversion (SVN), Git, MySQL, Ext JS, Node.js, JavaScript, PHPUnit, Zend Framework, PHP

Lead Developer

2011 - 2013
InvitedHome (formerly Vacation Rental Partner)
  • Paved a path and began moving the entire codebase from CakePHP to Ruby on Rails. Re-architected it and kept business needs moving forward.
  • Integral in building the back-end and parts of the front-end for a new guest-facing site, enabling VRP to pivot its business model.
  • Built custom feeds using REST, JSON, and XML to list VRP’s properties on HomeAway, FlipKey, and SkipJump through their proprietary APIs.
  • Built accounting tools to automate manual tasks that previously cost the CEO numerous hours every month.
Technologies: Ruby, JavaScript, CSS, Git, jQuery, RSpec, PostgreSQL, CakePHP, PHP, Ruby on Rails (RoR)

Website Developer, Consultant

2010 - 2011
Denver Homes Online
  • Worked with the client from the ground up to craft several web designs and implement them in a foundation the client could maintain.
  • Trained the client in digital marketing fundamentals, including key concepts of SEO and proper usage of analytics to track the performance of campaigns.
Technologies: JavaScript, CSS, Adobe Photoshop, Google SEO, Concrete5, PHP


2009 - 2009
  • Developed from scratch an MVC framework in PHP, complete with a custom ORM.
  • Built a social network foundation with user profiles. Implemented commenting and friending features.
Technologies: JavaScript, CSS, Subversion (SVN), jQuery UI, MySQL, PHP

Website Developer

2008 - 2008
Sito Marketing/American Vending Systems
  • Created and concurrently managed all the technical needs of ten websites.
  • Built a specialized CMS in PHP that allowed for fast generation of hundreds of landing pages.
  • Integrated leads coming from various sources into a Customer Relationship Management (CRM) system using PHP and a REST API.
Technologies: JavaScript, CSS, WordPress, SugarCRM, Subversion (SVN), Python, jQuery, MySQL, PHP

Website Developer

2007 - 2008
Colorado Home Helper
  • Developed a system for real estate agents to email clients custom home search reports using an AJAX-based interface and PHP/MySQL back-end.
  • Developed and further customized an existing PHP-based MLS to allow visitors to register and save searches. Integrated featured listings and improved overall functionality and usability.
Technologies: JavaScript, CSS, Subversion (SVN), jQuery, MySQL, PHP


A set of data structures used to manage complex relationships in JavaScript.


Praisee is a community dedicated to giving consumers a voice to share their reviews, ask questions, and find answers to all products

I co-founded Praisee and wrote the service from scratch on top of React.js, GraphQL/Relay, Node.js, TypeScript, PostgreSQL, Redis, and Google Cloud Platform. The front-end is isomorphic and the back-end is a custom scalable architecture designed for the unique batch data loading and authorization needs of GraphQL.


MetricLift automates advertising on Facebook by continuously sampling audiences and adjusting spend across hundreds of multivariate ad sets. We've been able to increase conversions for clients anywhere from 1.5x to 2x. I built the back-end with Python/Django which talks to various APIs such as Facebook's Marketing API and HubSpot's APIs.

Portfolio and Code Samples

A variety of previous projects and code samples to view.


Node.js, React, Facebook API, Facebook Ads API, Facebook Marketing API, MobX, jQuery, jQuery UI, NumPy, Stripe, Stripe API, SQLAlchemy, Pandas, Authorize.net, Devise, Socket.IO


JSX, Adobe Photoshop, Git, Elastic, Google Analytics, Moqups, Balsamiq, Mocha, Browserify, Chrome Developer Tools, Babel, Jira, RSpec, Vim Text Editor, Subversion (SVN), Concrete5, SugarCRM, IntelliJ IDEA, IPython Notebook, IPython, Jupyter, Sketch, InVision, Grunt, Gulp, NGINX, Trello, Apache


Express.js, Flutter, Electron, Redux, Django, Relay, Flux, Ruby on Rails (RoR), Zend Framework, Ext JS, CakePHP, Swagger, AngularJS, Bootstrap, PHPUnit, Laravel


TypeScript, ECMAScript (ES6), JavaScript, CSS, Python, PHP, GraphQL, ES7, Less, Sass, Ruby, SQL, Python 3, C++, C


Web Performance Optimization (WPO), Agile, Responsive Web Design (RWD), Object-oriented Programming (OOP), REST, Agile Software Development, MEAN Stack, Functional Programming, Kanban, Scrum, Model View Controller (MVC), Search Engine Optimization (SEO)


Elasticsearch, PostgreSQL, MySQL, Redis, SQLite, MongoDB


CentOS, Ubuntu Linux, Ubuntu, Docker, Windows, Heroku, Linux, MacOS, HubSpot, WordPress, Jupyter Notebook, Google Cloud Platform (GCP)

Industry Expertise

Social Media


Website Performance, RESTful Web Services, Front-end, Full-stack, Web Development, User Interface (UI), Front-end Development, Algorithms, Algorithm Development, Facebook Marketing, Facebook Ads, User Experience (UX), SOLID Principles, Digital Marketing, Google SEO, Google Tag Manager, Facebook, PIP, Customer Acquisition, Search Engine Marketing (SEM)

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