mintak son.

Engineer · Product leader

Mintak Son.

I build products.
And the teams behind them.

I joined Toss, South Korea’s #1 fintech super app, as an early engineer on a team of about 20 people. I built products as an engineer and Technical Product Manager (TPM), and grew its engineering chapter. After a Harvard MBA, I’m now building at the intersection of AI and the physical world.

LinkedIn (opens in a new tab)
Mintak Son, smiling in a light-colored jacket

A few chapters
along the way

Toss
Harvard
Business School
KAIST
SK Planet

Current focus

I’m focused on how AI can move physical products from design and CAD to prototyping and manufacturability.

I’ve interviewed 40+ companies, from consumer brands to manufacturers, to understand where AI can improve their workflows.

Experience

Engineering, product development, and leadership across startups.

Toss — toss.im (opens in a new tab) / Viva Republica

Software Engineer → iOS Chapter Lead → Technical Product Manager

2016–2026
Seoul, South Korea

South Korea’s #1 fintech super app: money transfers, banking, investing, insurance, and payments in one ecosystem.

$10B+ reported IPO valuation target (Reuters · July 2025)

An early engineer on a team of about 20.

When I left in June 2026, I was one of the eight earliest employees still at Toss, which had grown to 4,000+ people.

Product & engineering

Leadership & organization

Software Engineer, 2016–2018 · iOS Chapter Lead, 2018–2023 · Technical Product Manager, 2024 · MBA, 2024–2026

SimSimi

Full Stack Engineer · 2015–2016 · Seoul

Built across the iOS app, Android app, and backend for a conversational AI product with 22M+ monthly active users and a #1 app-store ranking in 19 countries. Initiated and commercialized a deep-learning profanity filter using a dataset of 15B+ sentences.

SK Planet, Frankly & MadSmart

Software Engineer · 2012–2015 · Seoul & San Francisco

  • Mobile messaging: Built core features for a messenger with 20M+ users as the third software engineer.
  • Frankly Chat: A founding-team engineer who built the product and connected the U.S. product team with Korean engineering.
  • SK Planet: Prototyped six mobile apps independently, including a location-based social app that launched.
  • MadSmart: Joined as employee #15 before its acquisition by SK Planet; selected as one of six core engineers for the U.S. team.

KOSFAN

Co-Founder · 2011–2012 · Seoul

Built a sports media platform’s CMS, tag-based search, and scheduling tools while owning product decisions. Partnerships with leading sports bloggers brought the platform to 100K+ page views.

Selected projects

Product decisions, engineering work, and customer discovery. Expand a project for the details.

At Toss

Toss · Product & engineeringRole: EngineerAccessible finance & the Toss design systemA customer visit became VoiceOver and Larger Text support, a reusable UI system, and 95%+ accessibility coverage.

My role: Initiated Customer-in-Person; championed accessibility and developed the design system.

The customer insight

Through the Customer-in-Person program, I brought teams into direct contact with people struggling to use Toss. Watching a visually impaired customer navigate the app revealed barriers our usual product reviews had missed. I also traveled across Korea to meet customers where they were.

The product decision

I advocated for accessibility when the immediate usage numbers made it easy to deprioritize. I connected the work to our goal of making finance easier for everyone, then tested on older iPhones used by visually impaired customers. The effort included VoiceOver, Larger Text, and a modular UI component library.

The result

The design system reached 95%+ accessibility coverage, and Toss’s accessibility work received government recognition. Reusable components also gave engineers a consistent foundation for building new product experiences.

Toss’s accessibility story (opens in a new tab)

Toss · Internal productRole: EngineerInternal data analytics & experimentation platformAn internal data product supporting real-time decisions across 1,000+ concurrent A/B tests.

My role: Proposed and guided development of the platform.

Build for how the company makes decisions

I evaluated existing analytics SaaS products and proposed an internal platform tailored to Toss’s needs. The goal was to make experimentation data useful to product teams in their daily decisions.

Scale the experimentation infrastructure

We built real-time analytics supporting more than 1,000 concurrent A/B tests. The work connected my engineering background with product judgment: deciding what teams needed to measure and building the tools that made those decisions practical.

Toss · Developer infrastructureRole: Engineering leadOne-click app deploymentAutomated internal app distribution 100+ times a day and established a weekly App Store release process.

My role: Created the deployment automation and release workflow.

Remove repeated release work

I built a one-click deployment system to make frequent internal distribution practical for a fast-moving team. The workflow connected development and coordination tools, including Jira, Jenkins, and Slack.

Make iteration a repeatable process

The system supported more than 100 internal app distributions per day and a weekly App Store release cycle. I presented Toss’s development and deployment environment in a recorded engineering talk in December 2017.

Watch the development & deployment talk (opens in a new tab)

Toss · New product initiativeRole: EngineerDigital identity & certificatesInitiated the PKI certificate authority project; the resulting system issued 30M+ certificates.

My role: Initiated the PKI certificate authority project.

Open a new product capability

The initiative explored how Toss could provide digital signatures and identity verification, extending its role beyond financial transactions into services used across public and private institutions.

Build within a regulated environment

The project required coordination across engineering, security providers, and government licensing requirements. It obtained digital-signature and identity-verification qualifications, and the resulting system went on to issue more than 30 million certificates.

Toss · Technical product management · 2024Role: TPMA group-wide financial accounting systemTechnical product ownership of an accounting system spanning eight subsidiaries and 50K+ transactions.

My role: Technical Product Manager; volunteered to take on the accounting-system project.

Choose a business-critical problem

I moved from engineering leadership into technical product management to work on problems that crossed technology and business operations. I volunteered to help build the next-generation financial accounting system as part of Toss’s IPO-readiness work.

Coordinate the full operating environment

The project brought together internal finance teams across eight subsidiaries, SAP consultants, and external auditors. I managed development and optimization for a system covering 50K+ transactions, with efficiency and financial transparency as core requirements.

Toss · Engineering leadership · 2018–2023Role: Engineering leadScaling the iOS organization from 3 to 28Hiring, onboarding, career development, and performance systems for a growing engineering chapter.

My role: iOS Chapter Lead; owned hiring and performance reviews.

Hire and develop the team

I grew the iOS team from 3 to 28 engineers, conducted 200+ technical interviews and 20+ final culture interviews, and invested in high-potential junior engineers through structured mentorship.

Make growth repeatable

I built documented onboarding, leadership-development paths, and a performance-evaluation framework. Senior engineers had opportunities to teach and learn through study groups; emerging leaders took on sub-lead responsibilities. First-year turnover among new hires fell below 10%.

Change how I led

Feedback from colleagues helped me become more deliberate about delegation, candid feedback, and supporting people before problems escalated. The goal was a team that could operate and develop its next leaders without depending on one person.

Toss · Cross-functional leadershipRole: TPMLocalization for Korea’s foreign residentsA company-wide initiative addressing product barriers for 2.2M underserved foreign residents.

My role: Created and led the localization taskforce.

Make inclusion an operating priority

I formed a taskforce to address the barriers foreign residents faced when using Toss. The opportunity concerned an underserved population of 2.2 million people in Korea.

Align teams across the group

I used firm-wide presentations and town halls to build support across subsidiaries, including customer service, banking, and securities. The work involved changing product workflows and coordinating the teams responsible for delivering the experience.

Independent & MBA projects

Venture exploration · Oct 2025–Jun 2026Finding a market for an AI forecasting modelCustomer discovery with large companies in the U.S. and Korea to test where forecasting could improve procurement decisions.

My role: Market exploration and customer discovery, working with three teammates.

Test the buying workflow

Across 15+ conversations with buyers, inventory managers, and industry experts, we explored food, agriculture, energy, chemicals, batteries, and metals. We iterated quickly on how a forecast could become a useful procurement decision.

Let the market change the thesis

U.S. buyers often managed basis and spreads through hedging, while our starting model forecast price direction. Buyers also valued scenario analysis and explainable rationale. I translated those findings into 16 testable hypotheses to guide the next experiments.

Startup GTM project · HBS Tough Tech Ventures · Spring 2026Go-to-market strategy for an AI CAD startupA distribution strategy grounded in how mid-market manufacturers evaluate and buy engineering software.

My role: GTM research, buyer segmentation, and channel recommendations.

Understand the buying committee

We mapped engineering leaders, family-business owners, and shop-floor engineers, and profiled 21 competitors. Each buyer group had a different role in approving, funding, or blocking adoption.

Sequence the distribution strategy

Our recommendations prioritized founder-led sales and trade-show conversations, followed by partnerships with robotics OEMs, systems integrators, and gripper manufacturers. We proposed a private trial with technical proof and a sales-assisted close, adapted to manufacturers’ existing workflows and intellectual-property concerns.

Independent prototype · 2025Automating the mobile-app feedback-to-fix workflowA prototype built with n8n and OpenRouter, connecting app reviews, Linear requirements, and GitHub pull requests, with human review at the end.

My role: Customer discovery and prototype development, with Jeffrey He.

Learn from app publishers

Through 25+ discovery interviews, we examined how lean teams handled maintenance across multiple mobile apps. Isolated AI tools often added review work and lost context between product planning and engineering.

Build the connected workflow

We used n8n to orchestrate the workflow and OpenRouter to access AI models: collect feedback, prioritize a task, write a requirement in Linear, generate a code change, and open a GitHub pull request. A person made the final merge decision.

Demonstrate it on a real app

We tested the prototype on Readest, an open-source ebook reader available on iOS and Android. It traced a pinch-to-zoom issue from a requirement to a code change and verified the fix in the iPhone Simulator.

Academic strategy research · MBAZapier & the AI-native workflow automation marketA co-authored academic analysis of Zapier’s strategy as AI agents, open-source tools, and enterprise platforms reshape automation.

My role: Research and co-authoring, with Kuma McCraw.

Analyze the strategic choices

We studied Zapier as the subject of an academic strategy paper. The analysis compared an SMB focus, proprietary models, open-source orchestration, a workflow marketplace, and on-premise capabilities.

Connect platform strategy to adoption

Our recommendations centered on small-business customers, a two-sided workflow marketplace, and a longer-term path for security-conscious customers. The project expanded how I think about reliability, distribution, and who creates reusable AI workflows.

Speaking

On startup life, engineering systems, and careers in fintech.

APR 2026

Harvard × MIT Korean Startup Meetup

Startup life as an early joiner

A decade inside Toss: early-stage engineering, learning through failure, and growing a team.

Talk outline

Shared with the Harvard and MIT Korean startup community on April 18, 2026. The talk followed my journey from an early engineering hire at Toss to chapter leadership and an MBA.

  • Choosing an early-stage company and living through its uncertain years.
  • Building resilience, learning to give candid feedback, and creating systems that support a growing team.
  • How early-stage lessons shaped my approach to products and teams.
Community talk
MAY 2022

Tutorial Week · Hosted by CareerHigh

A developer’s career in fintech

An introduction to fintech, product teams, and the day-to-day work of an engineer at Toss.

Talk outline

A career exploration session for people considering work in fintech, covering the industry, how product teams are organized, engineering responsibilities, hiring, and practical advice from my own experience.

Career lecture
DEC 2017

Toss · Engineering

Toss’s development & deployment environment

How we built the tooling and release process to help a fast-moving team ship.

Watch the talk (opens in a new tab)
Recorded talk

Education

Harvard Business School

Master of Business Administration

2024–2026 · Boston, MA

Section leadership. Tech, AI, Automation & Deep Tech, and entrepreneurship communities.

KAIST

B.S., Mechanical Engineering &
Business and Technology Management

2007–2015 · Daejeon, South Korea

Magna cum laude. Full entrance scholarship. President of the student ambassador organization; coursework in systems control and robotics.