Senior Software Engineer, Platform API - Ruby on Rails

At Treasure Data, we’re on a mission to radically simplify how companies use data and AI to create connected customer experiences. Our intelligent customer data platform (CDP) drives revenue growth and operational efficiency across the enterprise to deliver powerful business outcomes.

We are thrilled that Forrester has recognized Treasure Data as a Leader in The Forrester Wave™: Customer Data Platforms For B2C. It's an honor to be acknowledged for our efforts in advancing the CDP industry with cutting-edge AI and real-time capabilities.

Furthermore, Treasure Data 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.

Work the team does, and you will participate in:

• Design, ship, and operate Ruby on Rails Platform APIs end-to-end—from spec to rollout—meeting agreed availability/latency SLOs.
• Drive API design (OpenAPI/contract tests), versioning/deprecation, and compatibility for first-party UIs and partner integrations.
• Operate across the stack as needed, from backend APIs to front-end experiences, based on product needs.
• Ensure scalability, performance, and operationalization remain primary concerns throughout development.
• Keep up to date on novel technical concepts that we should adopt (and which ones we should ignore).
• Evaluate and introduce pragmatic improvements (framework/library upgrades, testing strategy, CI/CD/IaC) with clear trade-offs—in writing.

Your experience and skills will include:

• 5+ years of software engineering experience with a proven track record.
• Have the ability to work full-stack (from the DB all the way to the Frontend).
• Writing Web APIs in Ruby on Rails.
• SQL and working with and maintaining Relational Databases in a production environment.
• System architecture and design
• Knowledge of design patterns involving APIs that communicate with many backend components.
• Variety of testing approaches, correctness through design, and a holistic approach to quality.
• Cloud technologies (particularly AWS) and development/deployment in a cloud infrastructure.
• Write clear design docs and incident postmortems; communicate across time zones.
• Comfortable working in English and Japanese: can participate in team meetings, ask/answer questions, and write simple tickets/Slack messages in either language.

We would be thrilled if you had:

• Sense of project ownership and responsibility.
• Experience owning and leading short to medium-term technical direction across teams
• Business-level English proficiency and conversational-level Japanese proficiency
• Experience working in a different programming environment, such as the JVM (Java or Kotlin) or a different API style, such as JSON: API.
• Contributed to a production-grade web application handling high traffic.
• Experience in developing a fully managed cloud service.
• Experience with microservices-oriented architectures and authentication/authorization challenges.
• Made open source contributions.

Physical Requirements:

3 days at Treasure Data Office

About Treasure Data:

Treasure Data is the Intelligent Customer Data Platform (CDP) built for enterprise scale and powered by AI. Recognized as a Leader by Forrester and IDC, Treasure Data empowers the world’s largest and most innovative companies to deliver hyper-personalized customer experiences at scale that increase revenue, reduce costs, and build trust.

Through unique capabilities such as the Diamond Record, AI Agent Foundry, and AI Decisioning with Real-Time Personalization, Treasure Data enables marketing and CX teams to personalize cross-channel engagement in real-time, optimize marketing spend while increasing ROI, and drive customer lifetime value through more intelligent retention and loyalty.

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.