Senior Backend Engineer

**About the company:** As a Senior Backend Engineer, you’ll build all the aspects needed to empower our web apps for the experience aimed by our UX/UI Designers, aiming for an elegant and scalable system architecture while properly considering the phase of the product , taking a leading role on both how applications look as well as work - creating apps together with our users that solve their needs with a touch of joy. As a Senior Backend Engineer, you’ll join our team in crafting our efficient, stateless, and elegant gRPC/JSON web APIs, that deliver just the right amount of data to the frontend to deliver the most usable early rendering as speedily as possible. We believe that you prefer languages such as Go, Node.js/TypeScript or Python, working with the latest communication protocols such as gRPC and QUIC(now HTTP/3) and center your stack around open source technologies and Linux. Perhaps you like Docker and Kubernetes just as we do? You find new standards incorporated in HTTP/2 such as HTTP streaming fascinating from a usability perspective, but also from a frontend architectural view? You’ll take advantage of many of the latest trends in technology. Examples of technologies we’ve recently used include grpc-gateway for gRPC and HTTP API capable services, serverless products such as Cloud Run, GCS, Cloud Pub/Sub, Vertex AI on GCP, and LangChain, Agent Builder and Gemini for AI Agent. Maybe you’re interested in incorporating GenAI solutions into the app that you’re building? We also hope that you’re passionate about choosing the right tool for the problem no matter if it’s Golang, Python, Node.js or perhaps something else - just like us. Responsibilities Grooming, planning, estimating user stories & features with PM, PO and the rest of the team Making architectural decisions together with the team Coding, lots of coding (this position is more focused on backend development) Development of internal & external APIs (Go/Python) Construction of integrated data analysis platform (BigQuery) Design and operation of database tables operated on CloudSQL Integration of GenAI into internal services (AI Agent, RAG) Planning and implementing testing strategies Helping out with recruiting, onboarding and training new members Pushing the team to achieve even more by forming, evaluating and implementing new processes and policies Responding to incidents together with the team as a part of the on-call effort Requirements Business level proficiency in Japanese, or at least JLPT N2. Do note that the less proficient you are in Japanese we will require you to compensate with higher technical capabilities. At least 5 years of experience relevant to the position (If the university is in the field of telecommunication, information technology or computer science, the above experience would be sufficient; otherwise, an additional year would be required.) Experience with Go and/or Python Experience with data modeling utilizing database technologies such as MariaDB, PostgreSQL, MongoDB, Redis, etc. Experience with BigQuery or similar tools Experience with Docker. Experience with Linux. Experience with Git Experience with Google Cloud Platform and Amazon Web Services. Experience with working in a fully digital environment(chat communication, online task boards etc) Experience with utilizing technologies such as ChatGPT, Gemini or similar for information gathering and work optimization (creating documentation etc) and Coding Agents for coding support Able to commute to the office and work on-site. Nice to haves While not specifically required, tell us if you have any of the following. Development methodologies such as TDD, SOLID or SCRUM Experience with working as a part of a larger development team Experience with developing services incorporating AI Agents and RAGs Utilizing new protocols such as GraphQL, HTTP/3 or gRPC for client-server communication Experience with LangChain/LangGraph, Dify Experience with leading, or assisting in leading, a team effort Experience with working tightly with end-user and mapping complex user journeys Experience with modeling & maintaining non-trivial data models Experience with developing and maintaining Warehouse Management Systems Business level proficiency in English (TOEIC 800, CAE C+ or similar) Compensation ¥7,400,000 ~ ¥12,100,000 annually. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION Related jobs CADDi Vertical AI Products for the manufacturing industry Senior Software Engineer, Backend-Focused Full-Stack (Global Product Team)　 ¥8.5M ~ ¥12M No Japanese required Apply from abroad Partially remote Backend Software Architecture Tech Lead, Backend-Focused Full-Stack (Global Product Team) ¥10M ~ ¥14M No Japanese required Apply from abroad Partially remote Backend Full Stack React MakeLeaps Optimizing billing operations. Full Stack Engineer ¥5M ~ ¥8M No Japanese required Apply from abroad Fully remote Python React Kraken AI-powered operating system for utilities. Senior Software Engineer (Backend - Python/Django) No Japanese required Japan residents only Partially remote Backend Python AssetHub AI-powered 3D modeling for game asset creation. Applied LLM Researcher No Japanese required Apply from abroad No remote Game Development Machine Learning Python About Belong Inc. Belong Inc. Minato-ku, Tokyo Belong builds an ecosystem for refurbished mobile devices, combining its own factory operations with software engineering to improve efficiency and quality. Founded out of Itochu in 2017, the company has expanded internationally with a New York office, and its diverse team works across mobile, e-commerce, IoT, and AI. **Responsibilities:** Grooming, planning, estimating user stories & features with PM, PO and the rest of the team Making architectural decisions together with the team Coding, lots of coding (this position is more focused on backend development) Development of internal & external APIs (Go/Python) Construction of integrated data analysis platform (BigQuery) Design and operation of database tables operated on CloudSQL Integration of GenAI into internal services (AI Agent, RAG) Planning and implementing testing strategies Helping out with recruiting, onboarding and training new members Pushing the team to achieve even more by forming, evaluating and implementing new processes and policies Responding to incidents together with the team as a part of the on-call effort Requirements Business level proficiency in Japanese, or at least JLPT N2. Do note that the less proficient you are in Japanese we will require you to compensate with higher technical capabilities. At least 5 years of experience relevant to the position (If the university is in the field of telecommunication, information technology or computer science, the above experience would be sufficient; otherwise, an additional year would be required.) Experience with Go and/or Python Experience with data modeling utilizing database technologies such as MariaDB, PostgreSQL, MongoDB, Redis, etc. Experience with BigQuery or similar tools Experience with Docker. Experience with Linux. Experience with Git Experience with Google Cloud Platform and Amazon Web Services. Experience with working in a fully digital environment(chat communication, online task boards etc) Experience with utilizing technologies such as ChatGPT, Gemini or similar for information gathering and work optimization (creating documentation etc) and Coding Agents for coding support Able to commute to the office and work on-site. Nice to haves While not specifically required, tell us if you have any of the following. Development methodologies such as TDD, SOLID or SCRUM Experience with working as a part of a larger development team Experience with developing services incorporating AI Agents and RAGs Utilizing new protocols such as GraphQL, HTTP/3 or gRPC for client-server communication Experience with LangChain/LangGraph, Dify Experience with leading, or assisting in leading, a team effort Experience with working tightly with end-user and mapping complex user journeys Experience with modeling & maintaining non-trivial data models Experience with developing and maintaining Warehouse Management Systems Business level proficiency in English (TOEIC 800, CAE C+ or similar) Compensation ¥7,400,000 ~ ¥12,100,000 annually. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION **Requirements:** Business level proficiency in Japanese, or at least JLPT N2. Do note that the less proficient you are in Japanese we will require you to compensate with higher technical capabilities. At least 5 years of experience relevant to the position (If the university is in the field of telecommunication, information technology or computer science, the above experience would be sufficient; otherwise, an additional year would be required.) Experience with Go and/or Python Experience with data modeling utilizing database technologies such as MariaDB, PostgreSQL, MongoDB, Redis, etc. Experience with BigQuery or similar tools Experience with Docker. Experience with Linux. Experience with Git Experience with Google Cloud Platform and Amazon Web Services. Experience with working in a fully digital environment(chat communication, online task boards etc) Experience with utilizing technologies such as ChatGPT, Gemini or similar for information gathering and work optimization (creating documentation etc) and Coding Agents for coding support Able to commute to the office and work on-site. **Nice to have:** While not specifically required, tell us if you have any of the following. Development methodologies such as TDD, SOLID or SCRUM Experience with working as a part of a larger development team Experience with developing services incorporating AI Agents and RAGs Utilizing new protocols such as GraphQL, HTTP/3 or gRPC for client-server communication Experience with LangChain/LangGraph, Dify Experience with leading, or assisting in leading, a team effort Experience with working tightly with end-user and mapping complex user journeys Experience with modeling & maintaining non-trivial data models Experience with developing and maintaining Warehouse Management Systems Business level proficiency in English (TOEIC 800, CAE C+ or similar) **Compensation:** ¥7,400,000 ~ ¥12,100,000 annually. APPLY FOR THIS POSITION DO YOU NEED MORE INFO? ASK A QUESTION