Full Stack Software Developer - ContractorFime is a globally recognised international player providing deep expertise across digital payments, mobility services, and digital identity. We work with leading organisations worldwide to solve complex challenges, identify emerging opportunities, and future-proof their strategies.Our team of 900+ experts operates in over 20 locations around the globe, delivering solutions that support millions of transactions every day, across integral markets. What sets us apart is our values: we are curious, creative, and highly collaborative, with a strong commitment to integrity - we do the right thing for our clients, our people, and our shareholders.At Fime, the work is varied and intellectually stimulating. No two days are the same, and you will be surrounded by smart, engaged colleagues who value learning and continuous improvement.MISSIONYou will be a Senior Full Stack Engineer on a contractor basis on our cybersecurity Saa S platform that helps manufacturers and security teams certify Io T and connected devices against international regulatory standards. You will develop and evolve all layers of the product – React/Type Script frontend, Type Script client library, and Node.Js/Postgre SQL backend with AI‑assisted features – working closely with cybersecurity, testing, and UX specialists to deliver a secure, robust, and highly usable platform for a technically demanding user base.ACTIVITIES Develop and maintain features across the frontend (React, Type Script, Vite), the Type Script client library, and the backend (Node.Js, Express.Js, Postgre SQL).Design, build, and optimise RESTful APIs that power compliance workflows and AI‑assisted features.Work with Postgre SQL and ORM tooling (e.G. Sequelize)



to design reliable, well‑structured data models.Integrate compliance rule sets and machine‑processable workflows authored by the Cybersecurity Standards Engineer into the backend and client library.Integrate with third‑party services including AWS (S3, SES) and payment service providers.Maintain and improve CI/CD pipelines and containerised deployment environments using Docker and AWS, managing services across development, staging, and production.Participate in architecture and design discussions, contributing to decisions that favour long‑term maintainability, scalability, and security.Collaborate with the UI/UX Designer to deliver accurate, high‑fidelity implementations of designs.Support the Software Test Engineer by writing testable code and contributing to unit and integration test coverage using Vitest.Monitor and troubleshoot production issues, contributing to continuous improvement of reliability and performance. JOB EXPERIENCE At least 5 years of professional full‑stack software development experience; 10+ years strongly preferred.Proven experience building Type Script‑based applications across frontend (React) and backend (Node.Js, Express.Js).Solid experience designing and working with Postgre SQL databases and relational data models,



including use of ORM systems such as Sequelize.Hands‑on experience with AWS services (e.G. S3, SES, deployment infrastructure) and Docker‑based containerisation.Experience maintaining CI/CD pipelines and Git‑based workflows in a collaborative team environment.Understanding of event‑driven and queue‑based architecture patterns.Familiarity with product security standards such as ETSI EN 303 645 and ETSI TS 103 701; knowledge of FIDO or NIST specifications is a plus. Nice to have: Experience working on cybersecurity, compliance, or Io T‑related products.Background integrating payment gateways (credit card and/or e‑wallet providers).Hands‑on experience integrating AI or LLM features in a production Saa S context.Experience writing or maintaining Vitest test suites. KNOWLEDGE & SKILLS Degree in Computer Science, Software Engineering, or a related field, or equivalent practical experience.Strong proficiency in Type Script, React, Node.Js, Express.Js, Postgre SQL, Vite, and modern frontend build tooling.Good understanding of Dev Ops practices, CI/CD, Docker, and AWS‑based deployment environments.Comfortable working across the full stack and switching context between frontend, client library, and backend concerns.Strong sense of ownership for features end‑to‑end, from implementation through deployment and monitoring.Collaborative and communicative working style, able to work effectively with engineers, designers, and domain specialists.High attention to the security implications of implementation choices in a security‑sensitive product.Fluency in English; French or German is a plus. ContractContractor / Freelance, full time. Min 6 months contract#J-18808-Ljbffr

📌 Full Stack Software Developer (Madrid)
🏢 Fime
📍 Madrid