Senior Software Engineer

Fullstack Software Engineer (Python / TypeScript / React) 📍 Paris (Morning Laffitte) | Full-time | 2 remote days per week 🌍 Tech Team | Role split 70% backend / 30% frontend About Symbiotic Security Symbiotic Security is a cybersecurity startup helping developers write secure code through an AI-powered assistant integrated into their IDE and CI/CD pipelines. Our solution has two unique strengths: it provides developers with interactive training to understand vulnerabilities as they code, and it automatically detects and remediates security flaws introduced by generative AI tools such as GitHub Copilot. ➡️ Founded in April 2024 ➡️ 16 team members split between Paris (Tech team) and New York (Sales team) ➡️ Goal: 15 new hires by the end of 2026 Our offices are located at Morning Laffitte (Paris 9ᵗʰ) — bright open spaces with collaborative areas, a friendly atmosphere, and a focus on productivity. Tech Stack & Environment Backend: Python 3.12+ / Django (monolith, REST API) Frontend: TypeScript / React (SPA) for the frontend of the SaaS platform, Typescript for the IDE plugin Database: PostgreSQL Architecture: Monolithic - Hexagonal, DDD being introduced Tests: 94% backend coverage, 100% business logic covered Tools: Sentry, logs, traces, internal analytics Satellite services: CLI tools & AI agents written in Python Your Mission Contribute to both the backend (70%) and frontend (30%) of our SaaS product. Participate in the design and evolution of our hexagonal architecture and DDD approach. Collaborate closely with Abir (Engineering Manager), Minh Thang (Tech lead) and Édouard (CTO) on technical and product decisions. Work on diverse projects: REST APIs, CLI tools, AI agents, performance optimization. Lead continuous improvement initiatives, such as code reviews, automated testing, and release management. Offer technical guidance to team members, fostering a culture of learning and professional development. What We’re Looking For Core Skills Master's degree in Computer Science or related field. Proven experience (min 5 years) as a software engineer, with a strong track record of designing and delivering complex software systems, Python and TypeScript required ✅ Demonstrated expertise in backend development using Python. An experience of Django would be a strong plus. Demonstrated expertise in frontend development using Typescript / React. Solid SQL knowledge (PostgreSQL preferred) Appreciated Experience working with Product Manager, Product Designer, or UI/UX person. Strong grasp of clean code principles (SOLID, DRY, YAGNI) Understanding or curiosity for DDD Monitoring / logging / API optimization = big plus Comfortable using LLMs (ChatGPT, Copilot, Claude) Soft Skills & Mindset Early-stage startup mindset: autonomous, fast, impact-driven Curious, rigorous, and eager to understand before acting Strong communicator, collaborative, no ego Capable of challenging ideas and defending opinions constructively Product-oriented with a desire to build meaningful software Work-life balance valued What You’ll Have Achieved Timeframe Key Milestones 3 months First features shipped, ramp-up on the stack, contribution to testing pipeline 6 months Leading a technical scope, improving architecture, driving performance or monitoring initiatives 12 months Recognized internal expert / coach within the team Methodology & Culture Agile-ish organization (2-week sprints, continuous releases) Systematic code reviews Occasional pair programming Mix of maintenance, new features, and R&D work Monthly “Bug Day” (stress testing the product) “Cool down period” planned for internal tech projects 💡 AI culture: every developer is encouraged to use ChatGPT, Copilot, or Claude as part of their workflow. Team Our product team brings together diverse profiles working collaboratively: fullstack engineers, AI engineers, cybersecurity experts, product managers, and product designers: all coming from different backgrounds. 👩‍💻 MT – Lead Engineer 👩‍💻 Abir – Engineering Manager 👨‍💻 Édouard – CTO Team culture: Collaboration > hierarchy Technically demanding but kind environment No-ego culture Strong product–tech alignment Compensation & Benefits 💰 BSPCE (equity) available 🏥 100% health insurance coverage 🍽️ Swile meal card 💻 €500 equipment budget 🚲 Allowance for Sustainable Commuting (e.g., cycling, carpooling, public transport) 🏖️ RTT + paid vacation 🏡 2 remote days per week 🪴 Important opportunities for career advancement and professional development by being a pioneer within a new company. 🧑‍🔬 Strong product & engineering culture in the company. 🥂 Vibrant and inclusive company culture with regular team outings and events. ☝🏽 Chance to make a meaningful impact and shape the future of Symbiotic. 👭 Referral bonus: €2,000 Hiring Process We respect your time and will make it quick and efficient. All of that will be completed within two weeks. Call with our Talent Acquisition - Blanche - 30 minutes Meeting with our Engineering Manager - Abir - 45 minutes to 1 hour. On-site technical test with our tech lead - Minh Thang - 1,5 hour. Culture fit - Meeting with the CTO and lunch with the team - 2 hours Formal hiring proposal.