# Jeff Chern > Software Engineer with interest in climate science Location: Oakland, California, United States Profile: https://flows.cv/jeffchern Versatile, curious, quick-learning software engineer with: • ~15 years experience in a mix of autonomous driving, mobile full-stack, aerospace, point-of-sale, in corporate and small-startup environments • obsession with elegant, well crafted, beautiful code • an eye for shaping process and culture: how teams can work better together, be more productive, experience less chaos, drop fewer balls, etc. • master's degree coursework in AI/ML/Computer Vision as an aviation enthusiast and private pilot, I bring: • creative problem-solving, solutions in the face of physical, legal, and practical constraints • detailed planning while remaining flexible in execution • someone who intuitively weighs risks and risk-management as part of my engineering workflow ## Work Experience ### Senior Software Engineer @ Zoox Jan 2021 – Present I build data tools that allow AI/ML engineers to quickly quantify the impact of their work on self-driving performance, before any code hits the road. ### Software Engineer @ Mashgin Jan 2019 – Jan 2021 | Palo Alto, California, United States Mashgin is re-imagining the checkout experience through Computer Vision and a top-notch user experience. Features delivered: • Redesigned/refactored/rewrote the core "Checkout flow" on our self-checkout kiosks, stabilized it to run smoothly for ~750,000 monthly transactions. • Integrated with a fingerprint reader and 3rd party backend for identity/age verification. • Integrated credit card processing via two flows: (1) direct-access to Ingenico card readers, and (2) via a 3rd-party docker service, that supports more card reader models but is not as responsive in terms of possible UX integrations. The two flows were of entirely different designs, so it was a lot of work to get both of them working side-by-side in the same codebase (major refactor/rewrite of payments layer), while still handling stored-value payments and age verification as before. • Integrated with a 3rd party price/discounts/tax system to override ours during checkout. • Occasional fixes on API and UI Techs: Python 3, Redis, MySQL, PM2, Linux shell, Node.js, React Contributions to team processes: • Enhanced our in-house deployment system (Linux CLI in Python, web backend in Express, frontend in Vue.js) with support for sane version numbering, better logging for deployment failures. • Established Git code-review processes for development, and branching processes for supporting releases • Introduced CI/CD, lint, and unit tests • Upgraded from Python 2.7 to 3.5 • Introduced Python type annotations • Investigated countless problems for our front-line support staff ### Software Development Consultant @ K-Motion Jan 2018 – Jan 2019 | San Francisco, California, United States K-Motion produces wearable gyroscopic sensors and related software that enables golf enthusiasts and their coaches to take the guesswork out of training golf swings and correcting postures, by using motion recording, instant feedback as well as analysis. My projects: • rewrote event-reporting / data-collecting system, which was implemented redundantly, but inconsistently, in both VB.NET and C#. Backend was a Microsoft Azure Cloud-managed DB. • data sync for user accounts and training regimens prescribed by coaches. • misc work in Unity • misc work with 3d transforms/quaternions, to compute angles and velocities from raw sensor data. ### Senior Software Development Engineer @ Yahoo! Inc. Jan 2014 – Jan 2018 - Acquired by Yahoo in 2014, continued to work on Aviate. - Developed a "sensor library" for Android, encompassing GPS, Wifi, Bluetooth, Screen/Cable/Battery state, Music Playback, and Activity Detection (e.g walking vs driving); signals served as inputs for our context engine, to adapt the homescreen for the user throughout the day. - Greatly improved battery usage by optimizing GPS use (trading off responsiveness for battery versus quality of user experience); gathered battery stats from 100k+ real-world devices to test the effects of different battery-saving heuristics - Implemented a client-side context engine to reduce network calls by 90% ("thin-client" is great, but sometimes you need a "thick-client" :-p ) - Organized and moderated a recurring "technical deep dive" session for our team, where we could present and teach each other about the architecture and design of various features, as well as new dev tools, frameworks, paradigms/processing. - Mentored junior engineers in how to develop, debug, troubleshoot within the Android framework with our choice of libraries (e.g. Dagger 2 dependency injection, RxJava for asynchronous work) - Introduced "Reactive Programming" and the RxJava library to the team and codebase, used it to solve a slow start-up time issue in our app. - Championed Behavior Driven Development through unit tests (Robolectric + Mockito for mocking/stubbing + our dependency injection framework) - Pulled the team together during a difficult company transition (Verizon acquisition) to build and deliver a new prototype app in 8 weeks, while engineering and product management were still in a chaotic state. - Technical lead for 6 months on a sub-team of 3 engineers, building a news feed backend for our homescreen; included client APIs and integration, and data plumbing for future news personalization efforts. ### Software Engineer @ ThumbsUpLabs Jan 2013 – Jan 2013 | Palo Alto, California - 2nd engineering hire; we developed "Aviate" a home-screen for Android phones that surfaced useful apps and custom cards based on location, time of day, and other factors. - Implemented GPS location sensing using Google Play Services - Built diagnostic tools for analyzing and troubleshooting location accuracy. - Web API security using Keyczar library on Android and Python-Django backend. - Integrated Robolectric unit-testing and Robotium automation-testing frameworks, when both were in a very early stage (very little documentation, and it was poor/inconsistent/outdated at that!) - Performed production database migrations on tables with millions of rows. - General client and backend feature work ### Software Engineer @ Tableau Software Jan 2012 – Jan 2013 | Menlo Park - Enhanced command-line admin tools for Tableau Server in a mix of C++, Java, and Ruby. - Integrated single-sign-on login for Tableau Server's web backend, in Ruby on Rails. - Also worked with PostgresSQL databases, Jetty web server, and unit tests. ### Teaching Assistant @ Stanford University Jan 2010 – Jan 2012 CS 107 Systems Programming in C. Led weekly programming lab sessions; produced and narrated 1-2 hour video supplements every week; evaluated students' coding projects, and nurtured them on their path to becoming confident and conscientious developers. ### Software Engineering Intern @ Palantir Technologies Jan 2011 – Jan 2011 | Palo Alto Wrote test automation for the front-end of their security analytics tool. ### Software Intern @ Cisco Systems Jan 2010 – Jan 2010 | Milpitas, CA Developed part of a web-administration portal for the Cisco TelePresence offering. ### Engineering Intern @ AeroVironment Jan 2009 – Jan 2009 | Simi Valley, CA Milled aluminum, assembled test hardware, and wrote ground- and air-side software. ## Education ### Master of Science (M.S.) in Computer Science Stanford University Jan 2010 – Jan 2013 ### Bachelor of Science (B.S.) in Electrical and Electronics Engineering Stanford University Jan 2006 – Jan 2010 ## Contact & Social - LinkedIn: https://linkedin.com/in/jeff-chern-46420120 --- Source: https://flows.cv/jeffchern JSON Resume: https://flows.cv/jeffchern/resume.json Last updated: 2026-03-22