Flutter developer · Independent product builder

I build mobile products from idea to release.

I’m Yutaro, a mobile developer based in Mendoza, Argentina. I work across product strategy, UX, Flutter, backend systems, monetization, and release—turning early ideas into dependable products people can actually use.

View selected work Get in touch

Open to mobile and product engineering roles

Yutaro Sakairi standing on a salt flat during a solo trip through South America

4 productsbuilt from early concept onward

iOS + Androidshipped and maintained

End to endproduct, code, data, and release

3 languagesworking across cultures

How I work

One product, owned all the way through.

I’m most useful when a product needs both clear thinking and hands-on execution. I can frame the problem, make the interface understandable, build the system, and stay with it after release.

Frame

Understand the user, value, and constraints before choosing a solution.

Design

Turn complex behavior into a coherent experience with clear priorities.

Build

Connect Flutter UI, native integrations, backend state, and purchases.

Operate

Release, observe, support users, and improve without losing their progress.

What ties it together

I treat the product as one continuous system rather than a handoff between separate disciplines. That is especially important when real user history, offline behavior, and production migrations are involved.

Selected work

My clearest example of owning a consumer product from concept through production operations.

Postmarks turns everyday steps into progress along routes between real cities. I designed, built, released, and continue to operate the product across iOS and Android.

What I owned

Product strategy and UX/UI
Flutter architecture and implementation
Firebase backend and Cloud Functions
Purchases, analytics, testing, and releases

What made it complex

Native health-data integrations
Offline-first journey state
Collectible and achievement systems
Production migrations without lost progress

Visit Website

Postmarks home screen showing progress along a route

01 / 04

Walk a real route

Everyday steps move you between real destinations and toward the next arrival.

Role: Founder, product designer, and developer
Platforms: iOS and Android from one Flutter codebase
Status: Released and actively maintained

Product

A motivation loop built around place

Routes, arrivals, stamps, and Trail Finds give daily walking somewhere to lead without turning the experience into a generic fitness dashboard.

Engineering

State that survives real usage

Offline-first data, health-platform synchronization, cloud backup, purchases, and migrations are designed around protecting earned progress.

Operations

Ownership continues after launch

I handle analytics, user support, production debugging, store releases, and the decisions that keep the product understandable as it grows.

FlutterDartFirebaseCloud FunctionsRevenueCatMapboxPostHog

Earlier products

Experiments shaped by evidence.

Not every project should become a long-term product. These taught me when to narrow a concept, when to change direction, and when the responsible decision is not to scale.

Bonda

Social activity platform

I was the sole product builder for a platform designed to help people discover and coordinate local plans. Community research supported a Mendoza-focused pivot but exposed adoption barriers, so we chose not to force a public launch.

Trip Wizard

Travel-planning marketplace

I built and released a two-sided marketplace connecting travelers with local planners. It reached approximately 250 Google Play downloads before research showed the acquisition model would not scale.

Beyond the work

A path guided by curiosity.

Born in New York and raised in Japan, I moved to Seattle alone at 19 to study biology at the University of Washington. Research, environmental science, and a lifelong fascination with insects taught me to observe closely and let evidence change my mind.

In 2022, I left my job to volunteer at a butterfly garden in Costa Rica, then backpacked solo through Central America. Another solo journey took me across South America the following year. When I reached Mendoza, I decided to stay.

I began learning mobile development while working at Amazon. In Mendoza I finished Travel Wallet, my first product, then became the sole product builder behind Trip Wizard and Bonda alongside a longtime friend and co-founder in Japan. Postmarks grew from everything I learned along the way.

Experience

Experience that shaped how I work.

Product work, high-volume operations, and scientific research taught me to make decisions from evidence and remain responsible for outcomes.

Independent Mobile App Developer

Mendoza, Argentina

2024–Present

Built four consumer mobile products from concept onward, owning requirements, design, implementation, testing, monetization, analytics, and customer feedback.

Shipping Clerk · Amazon

Renton, Washington

2022–2023

Promoted soon after joining. Coordinated time-critical outbound work, trailer capacity, and changing priorities across a 100+ associate operation.

Research Scientist · University of Washington

Seattle, Washington

2019–2021

Co-led analysis for a peer-reviewed Ecosphere study, built an R Shiny comparison tool, contributed to TrenchR, and co-authored a microclimate data guide.

Accountant · El Centro de la Raza

Seattle, Washington

2021–2022

Supported accounting operations for a community organization serving Seattle’s Latino community before leaving to volunteer in Costa Rica.

Education

University of Washington

Bachelor of Science in Biology · Minor in Environmental Science and French · cum laude · GPA 3.81

Seattle · 2020

Contact

Let’s build something thoughtful.

I’m open to remote mobile development and product engineering roles, as well as selected contract work.

yutaro.sakairi@gmail.com Message me on WhatsApp View résumé