Senior Fullstack Engineer

Join to apply for the Senior Fullstack Engineer (Node.js, React) role at Symbiotic. About Symbiotic Symbiotic is the universal staking protocol enabling protocols to streamline decentralizing their stack. Symbiotic enables creating fully custom or templated staking integrations leveraging any asset and features such as slashing, redistribution, (liquid) restaking, as well as native staking. Over 40 teams including Spark, Hyperlane, and Avail are building on Symbiotic’s universal staking primitives secured by over $1bn in TVL. Our People We’re a tight‑knit team of experienced individuals at the forefront of crypto infrastructure. Our backgrounds range from security auditing and smart contract development to node operation, and we’re supported by Pantera Capital, Paradigm and CyberFund. We’re on the hunt for talented professionals to join our mission and strengthen our awesome team. As a fullstack engineer at Symbiotic you’ll take responsibility for all backend services, architecture, and reliability so the rest of the team can stay focused on new features and growth. Keep reading only if this sounds interesting This is a full‑time role under a traditional employment agreement; we do not work with contractors. What You’ll Do Fully own the entire backend of Symbiotic: architecture, services, APIs, databases, performance, reliability, and observability Design and build new services from scratch with zero hand‑holding Take complete responsibility for everything you ship: you are the go‑to person for any question or issue related to your code Ruthlessly focus on delivering maximum value; challenge requirements when needed Write exceptionally clean, simple, and over‑documented code Jump into React frontend work whenever required (we’re a small team; speed > strict boundaries) Proactively propose valuable features and improvements Collaborate closely with the team, accept feedback openly, and mentor others when needed Ensure everything is thoroughly tested and production‑ready (monitoring, logging, error tracking, security) Continuously improve performance, scalability, and developer experience across the stack Who You Are 4+ years of production experience as a backend or fullstack engineer with deep ownership of services. Expert in JavaScript and Node.js internals (event loop, streams, memory model, async primitives) Proven track record independently designing and shipping complete backend services end‑to‑end Strong production experience with modern Node.js frameworks (Fastify, Hono, Elysia, Express, NestJS) Advanced PostgreSQL skills: schema design, indexing strategy, query optimization, transaction handling Strong React + TypeScript frontend background Docker‑native, comfortable with CI/CD (GitHub Actions), basic Kubernetes knowledge Obsessed with clean, simple, heavily documented code; you write extensive tests and love helping QA with edge‑case scenarios Excellent at algorithms and data structures. Startup mindset: you jump into frontend, infra, or anything else needed to move the product forward Deeply care about business impact and always understand the “why” behind what you build Bonus: Web3 experience (EVM, ethers.js/viem, RPC providers, indexing) or working knowledge of Go/Python Attention Job Seeker Job scams are unfortunately common in our industry. A few things to note: All interviews are conducted on Google Meet; never on Discord, Zoom, or any other platform. We will always contact you from an @symbiotic.fi email address. If you’re ever in doubt, reach out directly to nick@symbiotic.fi. Seniority level Mid‑Senior level Employment type Full‑time Job function Engineering and Information Technology Industries Blockchain Services Location Paris, Île‑de‑France, France Referral program: Referrals increase your chances of interviewing at Symbiotic by 2x Get notified about new Full Stack Engineer jobs in Paris, Île‑de‑France, France. #J-18808-Ljbffr