Hybrid Senior Full-stack Engineer

at Ontologize

• Job title: Senior Full-stack Engineer
• Job type: Full Time
• Experience level: Senior
• Salary: €95,000 - €125,000 per year
• Degree requirement: Bachelor's Degree
• Tech skills: Java, JavaScript, Next.js, Postgres, Python, React, SQL, Go
• Location requirements: Hybrid, Paris, France

About the role

• Senior full-stack engineer developing a learning portal and AI-powered features for Ontologize. Collaborating across Python and Next.js to enhance training solutions.

Responsibilities

• Take ambiguous problems, decompose them, and deliver working software with minimal hand-holding.
• Build and maintain strongly typed APIs and well-modeled data systems.
• Work across the stack: Python backend, Next.js frontend, PostgreSQL, and our deployment infrastructure.
• Use AI tools daily to accelerate development, learn the codebase, and ship faster.
• Engage directly with end users and stakeholders to understand what actually needs to be built.
• Contribute to our DevOps practices and bring ideas for better tools and processes.

Requirements

• Strong experience in a backend language (e.g. Python, Java, Go, etc.).
• Strong data modeling and API design skills.
• Competency with SQL — you can verify state in a production database and unblock yourself.
• Familiarity with hexagonal/ports-and-adapters architecture, or demonstrated ability to adopt architectural patterns quickly.
• Familiarity with modern frontend development. React/Next.js, performance optimization (useMemo, useCallback), error boundaries, and thoughtful component design.
• Curiosity about DevOps. You don't need to be an expert, but you should want to understand how your code runs in production.
• Required English level: C1 minimum (CEFR) – must be comfortable participating in technical discussions and writing documentation in English.

Benefits

• 25 days of paid vacation per year + applicable public holidays.
• Additional RTT days where applicable based on work schedule and agreements.
• Generous company discretionary days to support work-life balance.
• Employer-paid complementaire santé (mutuelle) covering supplemental health costs (hospital, specialist, dental, optical), with 100% of the employee premium covered by Ontologize.
• Inclusive prévoyance (disability/death) coverage through Rippling EOR.
• You participate in France’s mandatory pension system via payroll contributions.
• Ontologize offers access to optional company savings and retirement vehicles when available through Rippling.
• Full reimbursement of public transport costs for commuting to work (above the mandatory 50% minimum).
• Sustainable mobility allowance up to €900/year to support eco-friendly commuting (bikes, carpooling, scooter, etc.) fully exempt from social charges within legal limits.
• Support aligned with French statutory parental leaves and additional company-level family support programs where applicable (e.g. bereavement leave).