Senior Backend Engineer

Your tasks

About the Position We are looking for a Senior Backend Engineer to design, develop, and maintain backend services and AI-powered applications. You will deliver new features, integrate AI capabilities, and improve the reliability, performance, and maintainability of existing systems.

This is a senior, hands-on individualcontributor role. You will write code, contribute to architectural decisions,and collaborate with cross-functional teams to turn product requirements andemerging AI capabilities into production-ready solutions.

Backend Development and Maintenance

• Build and maintain scalablePython services and secure RESTful APIs using FastAPI.
• Own features from technicaldesign and implementation through testing, deployment, and ongoing support.

• Extend existing applications,troubleshoot production issues, refactor code, and manage dependency upgradeswhile preserving API compatibility.
• Design and optimize databaseaccess, caching, and asynchronous processing.

• Implement authentication,authorization, input validation, and reliable error handling.

AI Application Development

• Integrate LLMs and other AIservices through provider APIs and SDKs, creating reusable interfaces forapplication teams.
• Design reliable APIs and toolinterfaces for AI applications, with well-defined input/output schemas,validation, and error handling.

• Develop AI workflows usingprompt orchestration, structured outputs, tool calling, and streamingresponses.
• Manage context limits, ratelimits, timeouts, retries, and provider failures to support reliable productionuse.

• Evaluate model and promptchanges against representative test cases, balancing output quality, latency,and cost.
• Design and develop multi-agentsystems and workflows, where appropriate, to address business requirements andautomate complex tasks.

Quality Delivery and Collaboration

• Write automated tests andmaintain regression coverage for backend services and AI integrations.
• Improve logging, metrics, andtracing to diagnose failures and monitor service performance and AI usage.

• Maintain CI/CD pipelines andcontainerized deployments in collaboration with infrastructure teams.
• Conduct code reviews, documenttechnical decisions, and mentor junior engineers.

• Partner with product, frontend,AI, and infrastructure teams to clarify requirements and deliver maintainablesolutions.

Requirements

Must Have

• 5+ years of professional backend development experience, including2+ years developing AI-powered applications or services, with demonstrated ownership of service design, productiondeployment, and ongoing maintenance.
• Strong Python and FastAPI expertise,including asynchronous programming, type annotations, Pydantic, dependencyinjection, and RESTful API design.

• Practical experienceintegrating AI APIs or SDKs, including prompt design, structured outputs, andstreaming or asynchronous workflows.
• Understanding of common LLMchallenges, including context management, hallucinations, prompt injection,rate limits, and token costs.

• Hands-on public cloud experience, suchas AWS, Azure, or GCP, including deploying and operating backend applications.
• Solid database skills withPostgreSQL or another relational database, including data modeling and queryoptimization.

• Working knowledge of secure APIdesign, authentication and authorization, and secrets management.
• Experience designing reliablebackend services and external API integrations, including concurrency control,timeouts, retries, idempotency, and rate limiting, with the ability to explaindesign tradeoffs.

• Experience with pytest orequivalent testing tools, Git, CI/CD, and Docker.
• Strong problem-solving skillsand the ability to independently navigate, extend, and improve an existingcodebase.

• Strong written and verbal communication skills in both English andChinese, with the ability to explain technicaldecisions and tradeoffs across teams.

Nice to Have

• AWS experience, particularly with S3,SageMaker, DynamoDB, ECS, CloudWatch, or Secrets Manager.
• Frontend development experience with Vue or React, including TypeScript or JavaScript.

• Experience with agentframeworks such as LangGraph, Pydantic AI, Claude Agent SDK, or comparabletools, including multi-agent orchestration, task delegation, and contextsharing.
• Experience withretrieval-augmented generation (RAG), embeddings, and vector databases such aspgvector.

• Experience deploying local orself-hosted LLMs using tools such as vLLM, Ollama, or llama.cpp.
• Experience with multimodal AI,including image, audio, or 3D generation.