Senior Python Full-Stack Developer (Python+React)

Luxoft; Barcelona; Presencial; EUR 50.000 - 70.000; Jornada completa

Descripción de la vacante

A leading tech services firm in Barcelona seeks a Senior Python Developer to facilitate the migration of a legacy system to a cloud-based Java environment for a major U.S. bank. The ideal candidate has over 5 years of Python experience, proficiency in FastAPI, and strong debugging skills. This position requires working from the office 5 days a week.

Formación

• 5+ years of proficiency in Python development.
• Experience in front-end development, preferably React, for migration dashboards.
• Strong problem-solving and debugging skills.

Responsabilidades

• Troubleshoot and debug issues in GenAI-powered code translation pipelines.
• Collaborate with the development and client teams for project goals.
• Maintain and optimize the RAG application for the migration process.

Conocimientos

Python development

FastAPI

Async programming patterns

Pydantic

Vector embeddings

Graph database experience

Excellent communication skills

Herramientas

React

Graph traversal algorithms

Descripción del empleo

Project Description

We 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.

Responsibilities

We 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 pipelines
• Collaborate with dev and client teams to ensure alignment with project goals and deliver high-quality solutions
• Maintain and fine-tune RAG application that supports the migration process, specifically optimizing LLM prompts for pattern recognition
• Build and maintain FastAPI-based microservices that orchestrate the migration workflow
• Implement RAG (Retrieval Augmented Generation) systems using LangChain / Langgraph / LlamaIndex for contextual code understanding
• Design stateful migration workflows using LangGraph / LangChain / LlamaIndex for complex multi-step transformations
• Mandatory work from the office 5 days per week

Mandatory Skills

• Experience 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 connections
• Async programming patterns for handling concurrent migration tasks
• Pydantic for robust data validation in migration pipelines
• Experience with vector embeddings and embedding models
• Vector database implementation for semantic search
• Graph database experience for code dependency mapping
• Building agents for code analysis, implementing custom tools for mainframe-specific transformations, creating chains for multi-step code migration
• Orchestrating stateful workflows for complex migration scenarios, managing checkpoints for long-running migrations, implementing conditional routing based on code patterns
• Building knowledge bases from documentation, implementing hybrid search for code pattern matching, creating custom retrievers for language specific contexts
• Implementing similarity search and semantic code retrieval systems
• Graph traversal algorithms for dependency analysis
• Strong problem-solving and debugging skills for identifying translation anomalies and semantic preservation issues
• Excellent communication skills for collaboration with client teams and explaining complex technical translations

Nice-to-Have Skills

• Deep understanding of HLASM instruction sets, macro definitions, and DSECT mappings
• COBOL and PL / I for understanding integrated mainframe systems
• Assembly language debugging and performance optimization
• Mainframe utilities (DFSORT, IEBGENER, IDCAMS)
• Experience with mainframe subsystems : CICS transactions, DB2 stored procedures, JCL batch processing
• Knowledge of z / OS internals, linkage conventions, and program calling standards
• Familiarity with EBCDIC to ASCII conversion, packed decimal (COMP-3) handling
• Experience in Java development, particularly Spring Boot, to understand target architecture requirements
• Familiarity with large-scale system migrations and modernization efforts, including phased migration strategies and dual-run validation
• Prior experience working in the banking or financial services industry, understanding core banking concepts, regulatory requirements, and transaction processing
• Knowledge of performance tuning and optimization in cloud environments, including auto-scaling strategies and cost optimization

Languages

English: B2 Upper Intermediate