Jiwoon Won

Engineer & founder building a layer that helps machines understand the real world | ex-Twelve Labs

Seoul, South Korea

About

Software engineer with 7+ years of experience, driven by a deep understanding of customer needs. Proficient in delivering high-quality products at a fast pace by collaborating with diverse stakeholders and communicating in clear, actionable terms. Strongly focused on product scalability and sustainability. Passionate about venturing into unknown territories and eager to grasp the fundamentals of businesses.

Experience

  • Co-founder, CEO at Stealth
    Oct 2025 - Present · 10 mos

  • Software Engineer at Twelve Labs
    May 2022 - Sep 2025 · 3 yrs 5 mos

    Joined as founding engineer right after getting $5M seed with 10 people in the office, and participated in building zero to many for 3.5 years - 150+ employees, $108M+ funding. - Spearheaded the development of the Playground from scratch and maintained ownership of the project for over 2+ years. - Contributed to enterprise projects, including collaborations with high-profile customers. - Supported the GTM team in resolving technical challenges faced by small business clients in the early stages. - Proactively identified product improvements and delivered them by leveraging a deep understanding of client-server interactions and inference systems.

  • Software Engineer at PPLINK inc.
    Jan 2021 - May 2022 · 1 yr 5 mos

    Built and led product engineering for Pagecall’s online education SaaS platform. Worked across customer-facing features, frontend architecture, sprint execution, and platform foundations. Helped grow the client base 4x, reduce bug reports by 75%, and turn an internal dashboard into a production SaaS platform that contributed to a $16.5K/month customer contract within three months. Built an in-house state management system for complex asynchronous workflows, introduced structured QA, and helped establish reusable foundations including authentication, frontend components, and a design system.

  • Lead Software Engineer at Ministry of National Defense, Republic of Korea
    May 2019 - Dec 2020 · 1 yr 8 mos

    Led development of an internal security incident analysis tool inside a restricted military network environment. The constraints were very different from a startup - limited infrastructure, strict deployment conditions, and technical users who needed reliability more than polish. I built interactive workflows for security analysis, deployed the product on bare-metal infrastructure, led engineering sprints, and mentored junior engineers.

  • 9th Trainee at SW Maestro
    Jun 2018 - Dec 2018 · 7 mos

    - Selected as one of 100 finalists for a prestigious 6-month developer training program. - Built a service to convert conversation into medical records using STT and LSTM models.