Full Stack Software Developer

Fime; España; Presencial; EUR 83.000 - 124.000; Jornada completa

Descripción de la vacante

Fime is seeking a Senior Full Stack Software Developer on a contractor basis to join our cybersecurity SaaS platform. You will work on the full stack: React/TypeScript frontend, TS client library, and Node.js/PostgreSQL backend, collaborating with cybersecurity, testing, and UX teams to deliver secure, scalable features for a technically demanding user base.

The role requires strong experience across the stack, a solid understanding of security standards, and hands-on expertise with AWS, Docker,

Formación

• 5+ years of full-stack software development; 10+ years preferred.
• Strong experience with TypeScript-based apps across frontend and backend.
• Experience with PostgreSQL databases and Sequelize ORM.
• Hands-on AWS (S3/SES) and Docker-based deployment.

Responsabilidades

• Develop and maintain frontend (React, TS) and backend (Node.js, Express) features.
• Design and optimise RESTful APIs for compliance workflows and AI features.
• Work with PostgreSQL and Sequelize to model data.
• Integrate AWS services and third-party providers.
• Maintain CI/CD pipelines and Docker deployments.
• Collaborate with UI/UX and test engineers; write unit/integration tests with Vitest.
• Monitor production and drive reliability improvements.

Conocimientos

TypeScript

React

Node.js

PostgreSQL

AWS

Docker

Educación

Bachelor's degree in Computer Science

Herramientas

Sequelize

Vitest

Express.js

Vite

Descripción del empleo

Full Stack Software Developer - Contractor

Fime 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 global 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.

MISSION

You will be a Senior Full Stack Engineer on a contractor basis on our cybersecurity SaaS platform that helps manufacturers and security teams certify IoT and connected devices against international regulatory standards. You will develop and evolve all layers of the product – React/TypeScript frontend, TypeScript client library, and Node.js/PostgreSQL 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, TypeScript, Vite), the TypeScript client library, and the backend (Node.js, Express.js, PostgreSQL).


• Design, build, and optimise RESTful APIs that power compliance workflows and AI‑assisted features.


• Work with PostgreSQL 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 TypeScript‑based applications across frontend (React) and backend (Node.js, Express.js).


• Solid experience designing and working with PostgreSQL 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 IoT‑related products.


• Background integrating payment gateways (credit card and/or e‑wallet providers).


• Hands‑on experience integrating AI or LLM features in a production SaaS 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 TypeScript, React, Node.js, Express.js, PostgreSQL, Vite, and modern frontend build tooling.


• Good understanding of DevOps 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.

Contract

Contractor / Freelance, full time. Min 6 months contract