Senior Python Full-Stack Developer (Python+React)

Project descriptionWe have an ambitious goal to migrate a legacy system written in HLASM (High-Level Assembler) from the mainframe to a cloud-based Java environment for one of the largest banks in the USA.ResponsibilitiesWe are looking for an experienced Senior Python Developer who can help perform the migration of the client platform:Troubleshoot, debug, and resolve issues in GenAI-powered code translation pipelinesCollaborate with dev and client teams to ensure alignment with project goals and deliver high-quality solutionsMaintain and fine-tune RAG application that supports the migration process, specifically optimizing LLM prompts for pattern recognitionBuild and maintain FastAPI-based microservices that orchestrate the migration workflowImplement RAG (Retrieval Augmented Generation) systems using LangChain /Langgraph/LlamaIndex for contextual code understandingDesign stateful migration workflows using LangGraph/LangChain/LlamaIndex for complex multi-step transformationsMandatory work from the office 5 days per weekSkillsExperience in front-end development (preferably React) for building migration dashboards and progress monitoring interfaces (2+ years)Proficiency in Python development (5+ years), with specific expertise in:FastAPI for building high-performance REST APIs and WebSocket connectionsAsync programming patterns for handling concurrent migration tasksPydantic for robust data validation in migration pipelinesExperience with vector embeddings and embedding modelsVector database implementation for semantic searchGraph database experience for code dependency mappingBuilding agents for code analysis, implementing custom tools for mainframe-specific transformations, creating chains for multi-step code migrationOrchestrating stateful workflows for complex migration scenarios, managing checkpoints for long-running migrations, implementing conditional routing based on code patternsBuilding knowledge bases from documentation, implementing hybrid search for code pattern matching, creating custom retrievers for language specific contextsImplementing similarity search and semantic code retrieval systemsGraph traversal algorithms for dependency analysisStrong problem-solving and debugging skills for identifying translation anomalies and semantic preservation issuesExcellent communication skills for collaboration with client teams and explaining complex technical translationsNice to haveDeep understanding of HLASM instruction sets, macro definitions, and DSECT mappingsCOBOL and PL/I for understanding integrated mainframe systemsAssembly language debugging and performance optimizationMainframe utilities (DFSORT, IEBGENER, IDCAMS)Experience with mainframe subsystems: CICS transactions, DB2 stored procedures, JCL batch processingKnowledge of z/OS internals, linkage conventions, and program calling standardsFamiliarity with EBCDIC to ASCII conversion, packed decimal (COMP-3) handlingExperience in Java development, particularly Spring Boot, to understand target architecture requirementsFamiliarity with large-scale system migrations and modernization efforts, including phased migration strategies and dual-run validation