10/20/2026 updated
100 % available
Senior Full Stack Software Engineer
Madrid, Spain
Only remote
Bachelor degree in Computer ScienceJava (Programming Language)LinuxNode.jsRedisNext.jsSQL DatabasesTypeScriptReact.jsExpress.jsVue.jsBackendAWS ECSFull Stack DevelopmentFront End Software DevelopmentApi Design
Full Stack Development with React and TypeScript
Extensive experience building modern web applications using React, TypeScript, and Node.js. Development of internal tools, CRM systems, and administration platforms, including migration of legacy React 16 class components to React 18 functional components.
Microservice Architecture and Backend Engineering
Design and implementation of microservice architectures, replacing legacy Java backends with TypeScript and Express. Development of flow-orchestration APIs, automated backups for sensitive databases, and modular backend services.
API Design and Third-Party Integrations
Design and documentation of external APIs alongside internal tRPC APIs for third-party integrations. Implementation of OAuth 2.0 integrations for Microsoft and Salesforce, and integration of Intercom into customer-support workflows.
Authentication and Security
Implementation of 2FA and additional security measures to harden authentication and protect user accounts. Configuration of Microsoft Active Directory SSO to standardize authentication across multiple products. Refactoring and securing modules responsible for highly sensitive access controls.
Frontend Frameworks and UI Development
Proficiency with Vue, Nuxt, React, NextJS, and TailwindCSS for building modern, polished user interfaces. Redesign of frontend applications to improve user experience and engagement.
DevOps and Developer Tools
Practical use of Git, AWS, CI/CD pipelines, Docker, Linux, and Neovim. Experience with Shell Scripting and managing cloud infrastructure.
AI-Assisted Development
Use of AI-assisted development tools including Claude Code and OpenCode to enhance productivity and code quality.
Accessibility and Compliance
Implementation of Spanish accessibility requirements for ATMs using the Windows Voice API, Electron, TypeScript, and React. Development of PCI-compliant logging and PAN obfuscation modules in TypeScript and Node.js.
Database and ORM Technologies
Experience with SQL, Redis, and TypeORM for data management. Implementation of automated backups for sensitive databases modified by multiple microservices.
Experience
Professional experience0 - 5 years
Freelancer since2022
Languages
EnglishFluentSpanishNative speaker
Project history
Provided Level 3 support and resolved production incidents across a broad microservice environment. Developed internal solutions to streamline fault-management team operations. Refactored and secured a module responsible for highly sensitive access controls. Implemented automated backups for sensitive databases modified by multiple microservices.
Implemented OAuth 2.0 integrations for Microsoft and Salesforce and integrated Intercom into customer-support workflows. Designed and documented an external API alongside the internal tRPC API for third-party integrations. Redesigned administration tools supporting business operations and group management.
Implemented 2FA and additional security measures to harden authentication and protect user accounts. Integrated multiple staking protocols including Lido CSM, Stader, and SSV Network. Refactored core backend services into modular, flexible components to accommodate evolving business requirements. Redesigned the frontend with a modern, polished UI to improve user experience and engagement.