Hello, I’m
Developer. Mathematics student.
Curious by nature.
I build software for data, learning, and travel.
Turning complex problems into tools that feel simple.
I’m Billy, also known as Zewen Liu. I’m studying Applied Mathematics at the University of Waterloo, with a specialization in Scientific Computing and Scientific Machine Learning.
I enjoy taking a problem apart, understanding how it works, and building something useful around it. That has taken me from Python backends and classroom tools to my current project: an iOS app for planning award travel.
Outside the code, I’m usually thinking about the next flight—and the best way to get there.
From supporting a classroom to building the systems behind it.
Waterloo, Canada
Beijing, China
A few things I’ve built, from the first idea to the details.
PUBLIC TESTFLIGHT · 1.0.0 (8)
A globe to explore.
An itinerary to understand.
A clearer way to plan the next trip.
Complex itineraries. Clearer answers.
A native iPhone and iPad app for planning multi-flight Aeroplan reward itineraries. Explore routes on a globe, look up flights and cached award availability, and understand points, stopovers, and connection times before booking.
Public testing is open. Contact me to receive a TestFlight invitation.
Request a test inviteA configurable Python client for finding Aeroplan award availability across routes, dates, cabins, and points budgets.
A C++ chess game built with a team of three, with synchronized console and X11 displays, custom setups, and pawn promotion.
An online letter-mailing service I built and operated, connecting website orders with real-world printing and delivery.
Bachelor of Mathematics
Applied Mathematics
Specialization in Scientific Computing
and Scientific Machine Learning
Python · C++ · C · SQL · JavaScript · Java · Bash · Swift
FastAPI · pandas · NumPy · Pydantic · Gradio · SwiftUI · MapKit
Git · Linux · MySQL · MinIO · Xcode · GNU Make
Résumé updated October 18, 2026.
HAVE SOMETHING IN MIND?
I’m always happy to talk about software, interesting problems, and ideas worth building.
Send me an email ↗