Senior Web Engineer

Senior Web Engineer Country: IT STARTS HERE Santander ( www.santander.com ) is evolving from a global, high-impact brand into a technology-driven organization , and our people are at the heart of this journey. Together , we are driving a customer-centric transformation that values bold thinking, innovation , and the courage to challenge what’s possible. This is more than a strategic shift. It’s a chance for driven professionals to grow, learn, and make a real difference . Our mission is to contribute to help more people and businesses prosper . We embrace a strong risk culture and all our professionals at all levels are expected to take a proactive and responsible approach toward risk management. Our Chief Data & Artificial Intelligence Officer (CDAIO) division is building a world-class AI & Data team to make a difference in the lives of over 170 million people worldwide, through one of the largest banks in the world. We are undergoing one of the biggest transformations in our history and technology is at the heart of our strategy. Join our team to play a part in one of the most important technological projects for the financial sector in the world. THE DIFFERENCE YOU MAKE CDAIO/ AI TECH is looking for a Senior Web Engineer based in Madrid. We are seeking a  Senior Web Engineer  to build advanced web solutions using  React  and  TypeScript . You will deliver concrete products — production web apps and  reusable, published packages/SDKs (npm)  — within the Grupo Santander platform ecosystem, applying solid  software architecture  and  CI/CD  practices to ensure quality, maintainability, and scalability. This role works on  product SDKs  (e.g. an AI chatbot React component) that sit on top of the shared Santander web platform, so the ability to read, integrate with, and reason about  platform building blocks  is essential. WHAT YOU’LL BRING Our people are our greatest strength. Every individual contributes unique perspectives that make us stronger as a team and as an organization. We’re enabling teams to go beyond by valuing who they are and empowering what they bring. The following requirements represent the knowledge, skills, and abilities essential for success in this role. Reasonable accommodations may be made to enable individuals with disabilities to perform the essential functions. Professional Experience A proven track record of at least 4 years of dedicated experience in web frontend development (React). (Required). Experience on projects composed of libraries or that publish packages/SDKs as a product. (Required). Demonstrable experience on projects with accessibility requirements. (Required). Experience limited to hybrid/mobile wrappers (React Native, Ionic, Cordova) will not be considered as web experience. (Required). Backend-heavy full-stack roles where the specific dedication to frontend cannot be determined will not be considered. (Required). Personal or freelance projects will not be considered unless carried out in a collaborative team environment. (Required). Languages Native level in Spanish. (Required). English — minimum B2 (B2–C1 strongly preferred). This is a strict requirement: all code, JSDoc/TSDoc, commits, PRs, changelogs, and platform documentation are written in English, and the SDK/platform is shared across international teams. (Required). Hard Skills Global: Mastery of  TypeScript  (strict mode, generics, discriminated unions, utility types, type-safe public API surfaces). (Required). Strong command of modern  JavaScript  (ES2022+, ES modules, async/await). (Required). Knowledge of  visibility and extensibility  / API-surface control (internal vs public boundaries, barrel exports, package.json exports map). (Required). Asynchronous and reactive models: Promises, async/await, AbortController, event streams (RxJS or signals a plus). (Required). Version control systems, preferably  Git . (Required). CI/CD tooling:  GitHub Actions  (or similar:  Bitrise , GitLab CI, Jenkins…).(Required). Agile development methodologies. (Required). PR creation/review workflow and QA quality-control practices. (Required). Architecture: Solid knowledge of component architecture patterns:  container/presentational , custom  hooks , unidirectional data flow, and finite  state machines  (XState a plus). (Required). State management:  Redux Toolkit ,  Zustand , or  Jotai  for client state and  TanStack Query  for server state. (Required). Solid grasp of best practices:  SOLID  principles,  design patterns ,  Clean Architecture , and clear separation of concerns. (Required). Development, deployment, and  version control of internal or public libraries  (publishing to  npm  /  JFrog Artifactory ;  semantic versioning ; awareness of public-API/type compatibility validation). (Required). Build & dependency management (library management) Build tooling:  Vite  for applications and library bundlers such as  Rollup ,  tsup , or  esbuild  for packages. (Required). Package managers:  pnpm  (workspaces), npm, or yarn — including lockfile discipline. (Required). Monorepo  tooling:  Turborepo ,  Nx , or pnpm workspaces. (Required). Module formats ( ESM/CJS  dual output), the exports field, type-declaration (.d.ts) generation and  API extraction  (API Extractor), and  tree-shaking  / bundle-size budgets. (Required). Dependency governance:  peer dependencies , automated updates (Renovate/Dependabot), version catalogs, and supply-chain security (npm audit). (Required). Data Access: Remote data:  fetch  /  axios  and  TanStack Query . Experience with  REST  and  streaming over SSE  (EventSource / fetch streams) is a strong plus. (Required). Real-time data:  WebSockets . (Required). JSON (de)serialization and runtime validation with  Zod  (typed DTOs). (Required). React: Advanced mastery of  React 18/19 , with demonstrable experience defining and building complex components and complete screens in