AI-Native Software Engineer

About the role

At Theodo, the AI-Native Software Engineer role centers on accelerating the migration of legacy systems into modern, secure, and scalable digital products. You will own the full lifecycle of AI-driven software delivery, partnering with clients to refactor legacy codebases into modular, cloud-native architectures. Using cutting-edge technologies, you will design and develop intelligent solutions that deliver measurable business value and exceed user expectations. You will lead technical investigations, mentor peers, and translate complex client problems into elegant, production-ready architectures. From day one, you will champion quality through robust tests, observability, and automation across the stack, while collaborating daily with product and design to align technical decisions with user needs and strategic goals. You will also contribute to industry-leading practices that shape how AI accelerates software modernization across Europe.

This role is based in Paris and requires availability for occasional travel within France and Europe for client visits and workshops. Candidates must be eligible to work in France under standard employment regulations, with no sponsorship required for this position. The hiring process will include technical assessments, interviews, and a practical coding exercise to evaluate real-world problem-solving abilities.

What you'll do

• Investigate and prototype AI-powered approaches to modernize monolithic legacy codebases into modular, cloud-native architectures.
• Lead the design and implementation of scalable backend services and responsive frontend interfaces using modern frameworks and languages.
• Collaborate closely with product managers and stakeholders to refine requirements, prioritize features, and validate hypotheses through experimentation.
• Implement automated tests, CI/CD pipelines, and monitoring solutions to ensure reliability, performance, and rapid, safe deployments.
• Analyze production telemetry and user feedback to drive iterative improvements and inform future product decisions.
• Explore and evaluate emerging tools, libraries, and platforms to keep Theodo at the forefront of AI-assisted software engineering.
• Mentor junior engineers by sharing knowledge, conducting code reviews, and fostering a culture of craftsmanship and continuous learning.
• Partner with cross-functional teams to align technical roadmaps with business objectives and client expectations.
• Champion security, compliance, and performance best practices throughout the development lifecycle.
• Document architectures, decisions, and processes to ensure transparency and enable seamless knowledge transfer.

Requirements

You hold a degree in Computer Science, Engineering, or a related field, or have equivalent practical experience. You possess solid full-stack development skills with a proven ability to build end-to-end features independently. You are proficient in at least one modern frontend framework and one backend language, with experience integrating systems via APIs. You have hands-on experience with cloud platforms, containerization, and infrastructure-as-code practices. You demonstrate strong problem-solving skills, with the ability to debug complex issues and optimize system behavior. You are comfortable working in fast-paced, ambiguous environments where priorities evolve quickly. You communicate clearly in French and English, both verbally and in writing, to collaborate effectively with diverse teams. You are passionate about learning and improving continuously, actively seeking feedback and applying it to your work.

Nice to have

Experience with AI-assisted development tools, large language models, or machine learning integration in software products. Knowledge of legacy modernization patterns, microservices, event-driven architectures, and DevOps practices. Familiarity with regulated industries such as finance, insurance, or healthcare where security and compliance are critical. Contributions to open-source projects or participation in technical communities, meetups, and conferences.

Key facts

-

Location: France

-

Engagement: CDI

• Theodo groups include software engineers, tech leads, engineering managers, and architects, collaborating in human-sized teams of 4 to 5 people.
• The practice AI Modernisation is the group's priority, focusing on accelerated migration of legacy systems using intelligent AI and a proven methodology.
• In 2025, the group generated €100M in revenue and has grown for 15 years, with over 850 Theodoers passionate about technology and continuous improvement.