Senior Python Developer

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

Descripción de la vacante

A leading IT services company is seeking a Senior Python Developer in Zaragoza, Spain. The role involves migrating legacy systems to a cloud environment, building FastAPI-based microservices, and collaborating with client teams. Candidates should have over 5 years of Python development experience, strong problem-solving skills, and excellent communication capabilities.

Formación

• Proficiency in Python development with 5+ years experience.
• Expertise in FastAPI for building high-performance REST APIs.
• Experience with async programming and Pydantic for data validation.
• Ability to troubleshoot and debug issues in GenAI code translation.

Responsabilidades

• Perform migration of client platform from legacy system to cloud.
• Collaborate with dev teams to align with project goals.
• Build and maintain FastAPI-based microservices.
• Optimize LLM prompts for logging and debugging.

Conocimientos

Python development

FastAPI

Async programming

Pydantic

Vector embeddings

Graph database experience

Problem-solving skills

Communication skills

Descripción del empleo

Overview

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

Skills

Must have

• 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 systemsGraph 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

• 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 front-end development (preferably React) for building migration dashboards and progress monitoring interfaces
• 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