Senior Software Engineer (Copy)

📍 Paris (Morning Laffitte) | Full-time | 2 remote days per week 🌍 Tech Team | Role split Full JS (Node/React) with mission-first contributions on Python services when needed 🚀 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. Our main products: Symbiotic Code — https://www.symbioticsec.ai/products/symbiotic-code Symbiotic Flow — https://www.symbioticsec.ai/products/symbiotic-flow ➡️ Founded in April 2024 ➡️ 24 team members split between Paris (Tech team) and New York (Sales team) ➡️ Goal: 10 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. 🎯 Your Mission Build and ship product features across our JavaScript/TypeScript stack (Node + React) for Symbiotic Code. Contribute to performance, reliability, and overall system design as we scale. Collaborate closely with Abir (Engineering Manager), Minh Thang (Tech lead) and Édouard (CTO) on technical and product decisions. Work on diverse scopes: APIs, portal features, IDE experience, CLI workflows, and internal tooling. Lead continuous improvement initiatives: code reviews, automated testing, CI quality gates, and release practices. Offer technical guidance to the team and help raise the quality bar. Mission-first mindset: we look for engineers who are ready to “cross the aisle”. If you’re a JS expert, you should be open to learning and contributing to our Python services when the mission requires it. 🌱 What You’ll Have Achieved 3 months First features shipped on the JS stack, strong ownership on a scope, confident navigation of the codebase and dev workflow 6 months Leading a technical scope end-to-end, raising testing discipline, driving performance/reliability improvements 12 months Recognized internal expert / coach on JS/TS architecture and delivery at scale ⚙️ Tech Stack & Environment Languages: JavaScript / TypeScript (primary) Frontend: React (portal / SaaS experience) Backend: Node.js (TypeScript) for APIs and services Testing: strong testing discipline (unit/integration, CI-driven) Nice to have: Python, Bun, OpenTUI Observability: logs / traces / monitoring (tooling in place; experience appreciated) 🧠 What We’re Looking For 🎓 Core Skills Proven experience (typically 5+ years ) as a software engineer delivering production systems. Strong track record in TypeScript/JavaScript ✅ Solid experience with React and Node.js (fullstack ownership) Strong engineering fundamentals: system thinking, pragmatic architecture, clean code, and delivery discipline Strong testing discipline and ability to design for maintainability 🎓 Appreciated Experience designing and operating asynchronous/distributed systems Observability / performance optimization / reliability mindset Comfort using LLM tools (ChatGPT, Copilot, Claude) responsibly Ability (and curiosity) to contribute to Python services when needed 💬 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 🧩 Methodology & Culture Agile 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 Technical “case” (Algorithm live coding + System Design) + debrief — 2 hours Culture fit - Meeting with the CTO and lunch with the team — 2 hours Formal hiring proposal