Sr Fullstack Developer(Django,react) For Japan based Product IT Company

Key Responsibilities:-

Own the design and development of complex features across both frontend and backend.

• Build and maintain frontend applications using React.
• Design and develop scalable backend systems and APIs using Python and Django.
• Take ownership of technical problems from initial investigation through architecture, implementation,testing, deployment, and production troubleshooting.
• Design solutions with future scale in mind, capable of supporting 100,000+ users, 10,000+ daily active users, and hundreds of concurrent users.
• Build and optimize systems that handle real-time user queries and high levels of concurrent application traffic.
• Identify and resolve application performance bottlenecks across frontend, backend, databases, APIs,and infrastructure.
• Work with databases, caching, asynchronous processing, queues, and other components required for scalable applications.
• Work closely with AI engineers to integrate AI models, LLM services, RAG pipelines, streaming responses, and other AI capabilities into the product.
• Improve the reliability, maintainability, observability, and performance of existing production systems.
• Participate in architectural and technology decisions as the platform evolves.
• Troubleshoot complex production issues and identify root causes rather than relying on temporary fixes.
• Contribute to code quality, engineering standards, testing practices, and technical documentation.
• Work flexibly across different engineering areas when required in a fast-moving startup environment.
• Work closely with senior engineering and technology leaders to design and evolve application architecture for new features and platform capabilities.
• Contribute to technical architecture discussions, evaluate different implementation approaches, and help make decisions considering scalability, performance, reliability, and maintainability.

Candidate Preffered:-

• Strong professional experience building and operating production web applications.
• Strong experience with React and modern frontend development.
• Strong backend development experience with Python and Django.
• Solid understanding of REST APIs, application architecture, databases, authentication, and backend system design.
• Experience designing or operating applications that support significant user traffic and concurrency.
• Good understanding of scalability concepts including caching, asynchronous processing, queues and background jobs, database optimization, load balancing, horizontal scaling, WebSockets or other real-time communication approaches, API performance, and rate limiting.
• Ability to independently investigate unfamiliar technical problems and determine an appropriate solution.
• Strong problem-solving mindset and willingness to work on problems where there may not be a direct or predefined solution.
• Ability to balance engineering quality with the speed required in a startup.
• Comfortable collaborating closely with product, AI, frontend, backend, and infrastructure teams.