Lead Fullstack Engineer - CDI Paris - AI-Modernisation

Tech Lead

Theodo accompanies innovative companies since 2009 in the conception, development, and deployment of ingenious digital products, leveraging the best of technology and the Lean approach. Our unique approach is based on three principles: we have developed recognized expertise in key technologies for product design and development; no matter the project stage, our priority in every decision is the creation of value for our clients;

we recruit the best digital talents and cultivate their ingenuity through the lean approach. Theodo has experienced exceptional growth over the past 15 years: our teams bring together more than 700 Theodoers, mainly software engineers, passionate about technology and continuous improvement. With growth, the group has structured itself into specialized entities by technology (Theodo Apps, Theodo Cloud, Theodo Data & AI) or by industry (Fintech, Govtech, Healthtech, Consumer Products Goods).

In 2025, the Theodo Group generates 100M€ of revenue.

The AI Modernisation practice is the Group's priority offer and carries Theodo's vision of becoming the European leader in AI applied to software development. Our business is the accelerated AI migration of old legacy systems to more modern languages and frameworks to reduce business, cybersecurity, and compliance risks that these systems may present. Thanks to mastered AI and a proven method, we go three times faster on the delivery of these critical projects.

If you want to join the future of tech, you are in the right place.

You will join a tech community of more than 350 Theodoers: software engineers, tech leads, engineering managers, and architects, with whom you can exchange, learn, and progress on a daily basis.

At Theodo, techs work in project teams, formed according to the needs of each client. You will be part of a human-sized Theodo team (4 to 5 people), bringing together software engineers, tech leads, and product managers. Together, you will collaborate closely with the client, with regular exchanges to share your progress, deepen the understanding of their problem, and evolve the product as closely as possible to the needs of its users.

The software engineering professions evolve with AI: come learn to become a Tech Lead AI Native.

We are recruiting a Tech Lead to design and develop useful, performant, and sustainable digital products to meet the challenges of our clients and their users.

As a Tech Lead, you are responsible for the rhythm and quality of your project delivery. You mobilize your team, make the technical choices adapted to the context, and support the Software Engineers in their progress, with the objective of growing both the product and the people who build it.

• Ensure project delivery and quality

You aim for a radically superior level of quality, structuring the delivery around standards:

• Design scalable and resilient architectures (clear and shared architecture diagrams)
• Write precise specifications to enable bug-free development of features
• Implement a quality strategy based on: clean code, automated tests, code reviews
• Ensure a structured work environment with the 5S principles (organization, clarity, efficiency)
• Accelerate development speed through the deployment of AI agents

• Be the technical partner of the client

Participate in project routines (backlog refinement, daily, ceremonies) and ensure continuous client satisfaction

• Explain and defend technical choices to create trust and align all stakeholders

• Create the performance conditions of the team

Implement an effective and structured work environment for the project team

• Set up problem-solving loops through Daily Problem Solving
• Create conditions for the team to leverage LLMs and gain productivity in their daily work

• Advance the Software Engineers of your team

Analyze in-depth the defects at the source to improve team knowledge (Dantotsu)

• Train and support the team (pair programming, code reviews, training)

The challenges are very different from one project to another, here are some examples:

• Health Hero:
  European leader in telemedicine, they wish to modernize their French platform, Qare, in view of a merger with the UK platform. The objective is to move from Loopback2 to Nest to upgrade from Node 10 to Node 20. Thanks to our AI-accelerated modernization method, we go from an estimate of 70 weeks without AI to a completed migration in 21 weeks and accelerate the delivery speed by 5.
• Pernod Ricard: wanted to modernize an internal application used to manage their marketing campaigns, millions of euros  impact of Theodo: 23 weeks to completely modernize the application from Vue Express to React Nest with a more pragmatic rewrite. We also performed the connection to their new ERP, previously impossible without the migration.

Two axes of evolution are available to you:

• Senior Architect: develop technical expertise
• Solution Architect: participate in the sale of complex projects by defining the most ingenious technical…