Senior AI Engineer with ReactJS

We are seeking a Senior AI Engineer with strong expertise in ReactJS and Python to join our team and help build, debug, and scale intelligent applications powered by LLMs and agent-based architectures. The ideal candidate combines deep backend engineering skills with a sharp eye for frontend quality and thrives on tracing complex issues across the full stack — from UI rendering to agent reasoning failures.

Responsibilities

• Design and build async endpoints, background tasks, and streaming responses using Python and FastAPI
• Develop and maintain agent-based systems, including prompt design, tool-calling, and RAG pipelines
• Diagnose and resolve LLM failure modes such as hallucination, context contamination, and non-deterministic output
• Tune retrieval quality through chunking strategies, embeddings, and vector search optimization
• Build and fix production-grade React UIs, including layout, responsive behavior, and streaming state management
• Identify and resolve concurrency issues, including shared mutable state and callback bleed under concurrent requests
• Operate within Docker and Kubernetes environments, including deployment and pod/log debugging
• Write and maintain test coverage using pytest and vitest, including mocks and fixtures
• Trace symptoms to root causes across frontend, backend, and agent layers to ensure system reliability

Requirements

• 5+ years of experience with Python, FastAPI, and asynchronous programming patterns
• Proficiency in agent frameworks such as pydantic-ai, LangGraph, or LangChain, with hands-on experience in prompt engineering and tool-calling
• Expertise in RAG systems, including chunking, embeddings, and vector search tools such as Qdrant or pgvector
• Skills in React (hooks) and CSS, with the ability to build and troubleshoot complex, responsive UIs
• Understanding of concurrency and state management, with experience implementing request-scoped state, locks, and thread-safety
• Familiarity with Docker and Kubernetes, including container management and deployment debugging
• Background in testing practices using pytest and vitest, with consistent use of mocks and fixtures
• Strong debugging skills with the ability to trace issues across frontend, backend, and agent layers
• English proficiency at B2 level or higher

Nice to have

• Experience with AWS Bedrock or other model gateway platforms beyond OpenAI
• Familiarity with Langfuse or other LLM observability tooling
• Knowledge of python-pptx or document generation tools for PowerPoint and PDF outputs
• Background in regulated industries such as pharma or life sciences, including familiarity with FDA PMA/510(k) and IVDR terminology
• Skills in Helm chart authoring and CI/CD pipelines using GitHub Actions
• Design sensibility for building premium, non-generic user interfaces
• Experience integrating SSO/OAuth solutions such as Azure AD or MSAL
• Familiarity with vector DB operations, including Qdrant collection management and embedding pipeline maintenance
• Understanding of prompt-eval or LLM-testing frameworks for measuring answer quality over time

We offer

• CONTINUOUS UPSKILLING, LEARNING & DEVELOPMENT
  • Diversity of tasks and projects
  • Assessment center for objective review of competency level
  • Personal development plan
  • Mentoring programs and leadership development
  • Certification and professional development support
  • Access to learning platforms including more than 2,500 internal courses
  • English courses taught by certified teachers
• CORPORATE BENEFITS
  • Extra leave days
  • Referral bonuses
• COMPENSATION PACKAGE
  • Competitive compensation paid in USD
  • Regular salary and performance reviews
• MEDICAL & HEALTHCARE
  • Private health insurance
  • Well-being events
• WORKING ENVIRONMENT
  • Recreation areas and kitchens
  • Tea, coffee and snacks
  • Sports equipment and game consoles
  • IT Equipment
  • Microsoft’s Software Assurance Home Use Program (HUP)

Please note that our Talent Attraction Team reviews applications and CVs submitted in English.

EPAM is a global leader in AI transformation engineering and integrated consulting, serving Forbes Global 2000 companies and ambitious startups. We deliver globally and engage locally, making the future real for clients, partners, and employees. We are proud to be recognised by Forbes, Glassdoor, Newsweek, Time Magazine, Great Place to Work and kununu as a Most Loved Workplace around the world.