SergioMartínAlonso
:: SENIOR_FRONTEND_DEVELOPER
Frontend developer with more than 10 years of experience, but previously designed buildings. Studied Architecture, which taught me to design with aesthetic judgment, to care about every visual detail, and to understand that what you see matters just as much as what lies behind it. When I discovered web development, everything clicked: I had been programming for years because I enjoyed creating with logic and building things that solved real problems. Bringing those two ways of thinking together is what defines how I work today.
Currently a Senior Frontend Developer specialized in Angular and TypeScript at Accenture, developing with AEM for international clients, with experience leading a frontend team. Care as much about clean code as about the final product making sense to the user. When code is well written, it shows: pages load faster, scale better, and are much easier to maintain.
Looking for teams where things are built with intention, where there is real learning, and where frontend is treated with the same level of seriousness as the rest of the product.
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Professional Experience
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Years Building Web Projects
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Web Projects Delivered
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Production Technologies
Technical Skills
HTML / CSS
Over a decade building interfaces from scratch: semantic HTML5 markup, advanced CSS animations and transitions, responsive design with Grid and Flexbox, and web accessibility (WCAG). Experience optimising render performance, using CSS custom properties for dynamic theming, and building coherent visual component systems in large-scale projects.
Exp:
14 years
Keywords:
HTML5, CSS3, Flexbox, CSS Grid, Responsive design, CSS animations, CSS variables, WCAG, BEM, Web Components, Media queries, Pseudo-elements, Keyframes
SCSS / LESS
Proficient in CSS preprocessors for maintaining scalable and maintainable styles in long-running projects. Advanced use of variables, parameterised mixins, functions, controlled nesting and modules. Defining style architectures based on methodologies such as ITCSS or the 7-1 pattern, ensuring visual consistency and ease of maintenance across multidisciplinary teams.
Exp:
6 years
Keywords:
SCSS, LESS, Mixins, Variables, Nesting, Functions, Partials, ITCSS, 7-1 pattern, Modules, Theming, Maps
JavaScript
Strong foundation in modern JavaScript from ES6 onwards: asynchronous programming with Promises and async/await, efficient DOM manipulation, design patterns (module, observer, factory), advanced closures and scope. Experience integrating REST APIs and WebSockets, optimising performance with debounce/throttle and lazy loading, and building complex business logic on the client side without unnecessary dependencies.
Exp:
14 years
Keywords:
ES6+, Async/Await, Promises, Event Loop, Closures, DOM API, Fetch API, WebSockets, ESM modules, Destructuring, Spread/Rest, Proxy, Iterators, Generators, Lazy loading
TypeScript
TypeScript adopted as the standard in Angular and Node.js projects to improve code robustness and the team development experience. Use of advanced types, interfaces, generics, decorators and utility types to correctly model each application's domain. Strict tsconfig configuration and definition of shared types between frontend and backend to ensure solid contracts between layers.
Exp:
6 years
Keywords:
Static typing, Interfaces, Generics, Decorators, Union types, Intersection types, Utility types, Enums, Type guards, Mapped types, Strict mode, Declaration files
Angular
Primary working stack for the past six years, with experience across Angular versions 8 through 19+. Development of complex SPAs with modular architecture, lazy loading and code splitting to optimise load times. Reactive state management with RxJS and signals, component communication, HTTP guards and interceptors. Integration with Angular Material, creation of reusable component libraries, and technical leadership of frontend teams on international projects with AEM and Magnolia CMS.
Exp:
6 years
Keywords:
Angular CLI, RxJS, Signals, Lazy loading, Guards, Interceptors, NgRx, Two-way binding, Change detection, Standalone components, Pipes, Directives, Angular Material, Modules, Resolvers, SSR, Angular Universal
React
Introductory knowledge of React aimed at understanding the ecosystem and being able to collaborate with teams that use it. Handling of functional components, basic hooks (useState, useEffect) and local state management. Ability to read, maintain and extend existing React code with sound judgement, supported by a strong JavaScript and TypeScript foundation.
Exp:
1 years
Keywords:
JSX, Hooks, useState, useEffect, Props, Functional components, Virtual DOM, Context API
PHP
Ten years developing backend solutions in PHP, mainly for personal projects and clients: REST APIs, member management systems, payment gateways (Stripe, Redsys) and content platforms. Experience with object-oriented PHP, session management and authentication, integration with MySQL and Firebase, and deployment on VPS servers and Google Cloud. Ability to maintain and scale legacy PHP projects without frameworks.
Exp:
10 years
Keywords:
PHP 8, OOP, REST APIs, Payment gateways, Authentication, PDO, Composer, Sessions, Cron jobs, cURL, Webhooks, MySQL integration, JWT, VPS deploy
Node.js
Development of REST APIs with Express for fullstack projects, particularly for the CD Bádminton Valladolid platform and personal projects. Implementation of middleware, JWT authentication, stream and event handling, integration with Firebase and relational databases. Deployment on Google Cloud and Docker containers, with experience automating processes such as notifications, registration management and scheduled tasks.
Exp:
6 years
Keywords:
Express, REST API, JWT, Middleware, Streams, Event Emitter, npm, dotenv, Nodemon, PM2, Cloud Functions, Firebase Admin SDK, CORS, Rate limiting
Spring Boot
Introduction to backend development with Java through Spring Boot, acquired during the Web Application Development programme. Creation of basic REST services, understanding of dependency injection, Spring annotations and Maven project structure. A starting point for projects requiring interoperability with Java enterprise environments.
Exp:
1 years
Keywords:
Java, Spring MVC, REST Controllers, Dependency injection, Maven, Annotations, Basic JPA
MySQL
Design and maintenance of relational databases in real projects with active users for over a decade. Normalised schema modelling, complex queries with multiple JOINs, subqueries and aggregation functions. Index optimisation for frequent queries, transaction management and referential integrity control. Experience integrating MySQL with PHP and Node.js in production environments.
Exp:
10 years
Keywords:
SQL, JOINs, Subqueries, Indexes, Transactions, Normalisation, Views, Stored Procedures, Foreign Keys, GROUP BY, Window Functions, Backup / Restore, phpMyAdmin
MongoDB
Use of MongoDB as a document database in projects where schema flexibility adds value, particularly in combination with Firebase and Node.js. Document modelling, basic queries and aggregation pipelines. Understanding of the differences between relational and document databases to choose the right tool based on the problem domain.
Exp:
1 years
Keywords:
NoSQL, Documents, Collections, Aggregation pipeline, Mongoose, ObjectId, Indexes, Lookup, $match / $group
Docker
Using Docker to containerise fullstack applications and simplify deployment across different environments. Creation of Dockerfiles for Node.js, PHP and Angular services, orchestration of multiple services with Docker Compose, and management of volumes and networks. Integration into basic CI/CD workflows and deployment on Google Cloud.
Exp:
2 years
Keywords:
Dockerfile, Docker Compose, Images, Containers, Volumes, Networks, Docker Hub, Multi-stage builds, Entrypoint, Env vars, CI/CD, Cloud Run
Google Cloud
Ongoing use of Google Cloud Platform as deployment infrastructure for personal projects over more than six years. Deploying Node.js and Angular applications on App Engine and Cloud Run, using Cloud Functions for serverless automations, managing storage on Cloud Storage, and configuring custom domains and SSL certificates. Integration with Firebase for authentication and real-time database.
Exp:
6 years
Keywords:
App Engine, Cloud Run, Cloud Functions, Cloud Storage, Firebase hosting, IAM, gcloud CLI, Serverless, Custom domains, SSL, Scheduler, Pub/Sub basics
Firebase
Integrating Firebase as a backend-as-a-service in personal projects to speed up development. User authentication with email, Google and custom tokens, Firestore for structured data and Realtime Database for real-time sync. Firebase Hosting for deploying Angular apps with caching and CDN, and Firebase Admin SDK in Node.js for server-side operations.
Exp:
2 years
Keywords:
Firestore, Realtime Database, Authentication, Firebase Hosting, Admin SDK, Security Rules, onSnapshot, Cloud Messaging, Storage, Emulator Suite
Git
Daily use of Git in multidisciplinary teams with structured workflows. Branch management with GitFlow and trunk-based development, conflict resolution in complex merges and rebases, pull request reviews with constructive feedback, and defining commit standards (Conventional Commits). Experience leading branching strategy in projects with multiple developers and continuous delivery cycles.
Exp:
2 years
Keywords:
GitFlow, Trunk-based development, Pull Requests, Code review, Rebase, Cherry-pick, Stash, Tags, Conventional Commits, GitHub, GitLab, Hooks, Merge strategies
Agile / Scrum
Working in agile environments both as a team member and, more recently, leading the frontend team at Serbatic. Active participation in all Scrum ceremonies: sprint planning, daily standups, backlog refinement, reviews and retrospectives. Managing Kanban boards to visualise workflow and identify bottlenecks. Focus on continuous value delivery and ongoing team process improvement.
Exp:
2 years
Keywords:
Scrum, Kanban, Sprint planning, Daily standup, Retrospective, Backlog refinement, User stories, Story points, Velocity, Definition of Done, WIP limits, Burndown chart
Jira
Using Jira as the central project management tool at Serbatic to coordinate frontend team work and communication with international clients. Creating and prioritising epics, stories and subtasks, configuring Scrum and Kanban boards, tracking sprint progress and generating velocity reports. Integration with Git repositories for traceability between commits and tickets.
Exp:
2 years
Keywords:
Epics, User stories, Subtasks, Sprints, Kanban board, Custom workflow, JQL, Filters, Dashboards, Git integration, Releases, Roadmap
Figma
Using Figma both to design and to consume designs as a developer, bringing a genuine understanding of design systems from both sides. User flow prototyping, creation and organisation of components with variants, collaboration on design systems and export of optimised web assets. An Architecture background reinforces the aesthetic judgement applied to every project.
Exp:
10 years
Keywords:
Prototyping, Auto Layout, Components, Variants, Design tokens, Design system, Frames, Inspect, SVG export, Real-time collaboration, Plugins
Illustrator
Proficient in Adobe Illustrator for creating visual identities, logos, graphic material for sports events and vector assets for the web. Applied experience at CD Bádminton Valladolid designing posters, banners and brand elements for over nine years. Combined with Photoshop for complete graphic production workflows.
Exp:
10 years
Keywords:
Vectors, Bezier, Corporate identity, Logos, Typography, Guides & grids, Symbols, Blend modes, SVG / PDF export, Artboards, Image trace
Photoshop
Fifteen years using Photoshop for photo retouching, digital compositing and production of graphic assets for web and events. Working with layers, masks, non-destructive adjustments and automated actions. Applied to creating graphic materials for the badminton club, architecture projects and corporate websites, always maintaining visual consistency with the brand identity.
Exp:
15 years
Keywords:
Layers & masks, Photo retouching, Digital compositing, Non-destructive edits, Smart Objects, Actions, Web export, Colour modes, Filters, Typography, UI assets
AutoCAD
Professional use of AutoCAD during the Architecture training and practice period to produce 2D technical drawings: floor plans, elevations, sections and construction details. Layer management, reusable blocks, dimensions and standardised annotations. This technical background in precise documentation translates today into the attention to detail applied to frontend development and interface visual organisation.
Exp:
10 years
Keywords:
2D drawings, Layers, Blocks, Dimensions, Annotations, Construction details, Layouts, Plot / PDF, Scale, Xrefs, Hatch, Technical documentation
Revit
Introduction to BIM modelling with Autodesk Revit during the Architecture degree, used in academic projects for multidisciplinary coordination. Creation of building models with families, views and associated plans. Understanding of the collaborative BIM workflow and its implications for construction project management.
Exp:
2 years
Keywords:
BIM, Families, Views, Plans, Coordination, Parameters, IFC, Levels, Phases, Basic render
Career Timeline
Personal Projects
Fullstack — Valladolid, Spain- Developed web applications from scratch using HTML, CSS, and JavaScript.
- Built full-stack websites using PHP and Angular, including payment gateway integrations.
- Developed corporate websites, landing pages, and internal management tools.
- Angular
- TypeScript
- RxJS
- NgRx
- Node.js
- Express
- PHP
- Java
- MySQL
- Firebase
- Docker
Web Manager & Graphic Designer
CD Bádminton Valladolid — Valladolid, Spain- Owned full-stack development and maintenance of the club's website and internal systems.
- Delivered end-to-end solutions using Angular, Node.js, PHP, Firebase, Google Cloud, MySQL, and Docker.
- Automated registration workflows and membership management, reducing manual overhead.
- Led graphic design and digital communication strategy across social media and events.
- Angular
- TypeScript
- RxJS
- Node.js
- PHP
- MySQL
- Firebase
- Google Cloud
- Docker
- Photoshop
- Illustrator
Frontend Developer
Serbatic — Valladolid, Spain- Developed and maintained projects using Angular, WordPress, Magnolia CMS, and Adobe Experience Manager (AEM).
- Led a frontend team on large-scale projects, coordinating delivery and code quality.
- Applied Agile methodologies (Scrum & Kanban) within collaborative, cross-functional workflows.
- Used Git for version control and team collaboration across multiple concurrent workstreams.
- Angular
- TypeScript
- RxJS
- AEM
- Magnolia
- WordPress
- SASS
- LESS
- MongoDB
- Docker
- Scrum
Frontend Developer
Accenture — Madrid, Spain- Frontend development and maintenance with Angular on Adobe Experience Manager (AEM) for enterprise clients.
- Component integration, publication lifecycle and production incident resolution within Agile teams.
- Angular
- TypeScript
- AEM
- JavaScript
- LESS
- Git
- Scrum
Academic Records
Higher Technician in Web Application Development
Dates:September 2021 — June 2023
Institution:IES_GALILEO
Location:Valladolid, Spain
High School Diploma — Science Track
Dates:September 2009 — June 2011
Institution:IES_JULIAN_MARIAS
Location:Valladolid, Spain
Bachelor's Degree in Architecture
Dates:September 2014 — June 2019
Institution:UNIVERSIDAD_DE_VALLADOLID
Location:Valladolid, Spain
Performance is not optional. It's structural.
I design and build frontend architectures where performance is a first-class concern. From bundle strategy to rendering optimization, every decision is intentional and measurable.
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Selected Projects
A selection of the most interesting projects I have developed.
Freelance
Web application bridging users and administrators of a private sports facility: bookings, services and events in one place.
Serbatic
Frontend development for the corporate website of an insurer operating in over 50 countries, leading a three-person frontend team.
Serbatic
Frontend for the web portal of a multinational leisure group with parks across several continents, integrated into Adobe Experience Manager.
