Treasure AI:

Treasure AI is the agentic experience platform built to acquire, retain, and grow your most valuable customers. Powered by AI, Treasure AI is shaped by human creativity and always-on through continuous, context-driven action.

Furthermore, Treasure AI employees are enthusiastic, data-driven, and customer-obsessed. We are a team of drivers—self-starters who take initiative, anticipate needs, and proactively jump in to solve problems. Our actions reflect our values of honesty, reliability, openness, and humility.

Your Role

We are looking for a Staff Fullstack Engineer to join our high-performing team working at the intersection of our Realtime and Personalization products. This is a pivotal moment for our platform: you will help drive the technical direction as we build an AI-native system, developing true, industry-leading systems that empower marketers to build in new ways.

In this role, you will act as a high-level individual contributor and technical anchor within a squad-based model. While your core expertise may lay in either complex frontends or robust distributed backend systems, you possess the architectural vision to design and mentor others across the full stack. This is a hands-on, high-impact role. You will work out of our Tokyo office three days a week, collaborating directly with product managers and designers to ship features that have a tangible impact on our customers' ability to generate value from their data.

What You Will Do:

• Drive the end-to-end technical architecture for our product features. You will make high-stakes technical decisions that balance speed of delivery with long-term maintainability.

• Ensure a focus on outcomes and ensure your squad is unblocked whether it is frontend or backend code and provide technical guidance to your peers.

• Deeply focus on design across the entire stack. You will weigh in on how React applications should be structured even if you are working on the backend to ensure consistency across the entire stack and unblock every engineer in your squad.

• Partner with Product Managers and Engineering Managers in a squad model to deliver projects on time. You will break down complex requirements into executable engineering tasks. You may serve as a tech lead for a squad.

• Elevate the engineers around you. You will mentor Senior and mid-level engineers, modeling best practices in code review, design patterns, and operational excellence.

• Build with a mind toward scalability, observability, and security. You will join the on-call rotation and treat production operations as a first-class citizen.

About You:

• 8+ years of software engineering experience, with a strong track record of shipping complex products.

• Deep proficiency in backend development (experience with Ruby, Go, Java, or Kotlin is preferred). You understand database design, and API scalability and as a strong bonus have dealt with distributed systems or LLMs in production.

• You have strong architectural knowledge of the React ecosystem. You may prefer backend work, but you understand how to build a frontend architecture that is modular and testable and are able to mentor engineers in React best practices.

• You thrive in agile, collaborative environments. You are a driver—you identify blockers and remove them.

• Basic-level English(conversational) is required. You can effectively communicate complex technical concepts to non-technical stakeholders.

Preferred Qualifications:

• Experience building or integrating Generative AI/LLM solutions into production workflows, especially with agents.

• Experience with Ruby on Rails is a significant plus.

• Experience with distributed systems.

• Experience working in global teams, coordinating with engineers in different time zones.

What We Offer

• Opportunities for leadership growth, technical mentorship, and introducing new processes.

• Work with specialists in varied fields—from designers to product managers—to make a powerful product used by major international companies.

• A flexible and exciting work environment with a hybrid model and competitive benefits.

Physical Requirements:

3 days in Treasure AI Office

Our Dedication to You:

We value and promote diversity, equity, inclusion, and belonging in all aspects of our business and at all levels. Success comes from acknowledging, welcoming, and incorporating diverse perspectives.

Diverse representation alone is not the desired outcome. We also strive to create an inclusive culture that encourages growth, ownership of your role, and achieving innovation in new and unique ways. Your voice will be heard, and we will help amplify it.

Agencies and Recruiters:

We cannot consider your candidate(s) without a contract in place. Any resumes received without having an active agreement will be considered gratis referrals to us. Thank you for your understanding and cooperation!