Senior Software Engineer

Mark Yamashita

I solve difficult engineering problems across platforms, from user and product needs through systems and implementation. I favor pragmatic architecture, root-cause debugging, and adding complexity only when the outcome requires it.

View selected work View experience
iOS & mobile · Backend & platform · Realtime systems · Unity · Networking · Developer tooling

How I solve problems

I enter a problem where it presents itself, then move between the user outcome and the implementation until the unknowns become something concrete to build, test, or fix.

Move in either direction as the evidence requires

  1. Goal / user need
  2. Product / experience
  3. System
  4. Subsystem
  5. Feature / state
  6. Implementation / diagnosis
Reduce uncertainty. I separate what I know, what I can learn, and what is a genuine risk that should be investigated early.
Follow evidence to the cause. I use reproduction, instrumentation, profiling, tests, and state inspection rather than treating a disappearing symptom as a solution.
Choose the appropriate solution. I cross technical boundaries when necessary, preserve diagnosability, and add abstraction or complexity only when the problem justifies it.
Communicate and preserve the why. I surface ambiguity and risk early, adapt explanations to the audience, and leave useful context in code, commits, diagnostics, and documentation.

Selected work

PariMAX WebGL HHR Client

1/ST Technology · C# · Unity WebGL · gRPC-Web · SDK design

The company’s first browser product could not use its existing .NET gRPC path inside Unity WebGL. I isolated that communication risk with a focused proof of concept, then turned the proven approach into a maintainable production SDK.

  • Bridged Unity C# to generated JavaScript clients through .jslib interop, Webpack, and browser-compatible gRPC-Web transport.
  • Kept Editor and WebGL workflows behind shared typed abstractions while preserving structured diagnostics, validation, and resilient retry behavior.
  • Reproduced failures across client, browser, proxy, and backend boundaries, instrumented those boundaries, and traced issues to their root cause.
  • Enabled the first WebGL product and delivered a reusable networking layer adopted across games.

TeachMe iOS Series

24x7digital · Objective-C · UIKit · Swift · SwiftUI · Firebase

Many TeachMe users were young children who could not yet read and had little or no experience using an iPhone. I designed the experience from the child’s point of view so they could use it independently and genuinely learn. The series reached more than two million downloads.

  • Mimi, an animated teacher mouse, gave contextual spoken guidance when a child needed help and receded as they demonstrated understanding.
  • For addition, children could count two groups of objects and watch them physically combine, using interaction to reveal the concept rather than reproduce a worksheet.
  • Balanced child independence and rewards with parent-visible learning progress, while supporting real customers through years of platform changes.
  • Built custom learning technology, including handwriting and stroke interactions before suitable standard libraries were available.

Job Search Agent

Personal system · TypeScript · Structured prompts · JSON · Document automation

Built an end-to-end agentic workflow that turns job listings and persistent candidate evidence into structured decisions and tailored application materials, with explicit validation and human ownership instead of unconstrained generation.

  • Designed persistent specifications, structured prompts, and JSON data stores for ingestion, evaluation, candidate context, and repeatable decisions.
  • Automated resume, cover-letter, and PDF generation while preserving source-backed claims, review checkpoints, and reproducible artifacts.
  • Added validation that catches inconsistent scoring, unsupported claims, and malformed enrichment data before it enters the canonical record.

Experience

Senior Software Engineer

1/ST Technology – AmTote International · Remote

2023 – Present
  • Led the networking path for the company’s first browser product and developed the reusable C#/JavaScript gRPC-Web SDK used across games.
  • Created an HHR game registry and implementation-neutral feature specifications so AI-assisted work can compare proven implementations and known issues across dozens of independently evolved games.
  • Authored the Unity team’s Claude Code quickstart and adoption guidance, emphasizing scoped context, Git-based review and rollback, runtime verification, and developer ownership of generated changes.

Lead Software Engineer

24x7digital · Los Angeles, CA

2008 – 2025
  • Owned product direction, architecture, implementation, App Store delivery, and long-term iteration for consumer iOS products with more than two million downloads.
  • Built custom learning interactions and data flows, integrated Firebase services, and evolved Objective-C/UIKit applications with Swift and SwiftUI.
  • Balanced customer feedback, platform changes, release quality, monetization, and maintainability across a long-lived product portfolio.

Software Engineer

Igloosoft Games · Remote

2021 – 2023
  • Shipped C# gameplay and simulation systems for Farworld Pioneers across PC, Mac, Xbox, and PlayStation.
  • Implemented creature AI, animation, pathfinding, and multiplayer systems, then profiled memory and CPU/GPU performance across platforms.
  • Built editor tools that improved world-generation and content workflows for designers and engineers.

Contact

I’m interested in senior software engineering roles across mobile, platform, product, and realtime systems.

Email: yama@yama.com

LinkedIn: linkedin.com/in/markyama