👋 Hi, I'm
📍 Barcelona, Spain
Full-stack developer with 6+ years building and shipping production SaaS. Backend with Symfony/PHP and API Platform, frontend with React/Next.js and TypeScript. Experience in multi-tenant architectures, payment integrations (Stripe), tax compliance (Veri*factu/AEAT) and applied AI (RAG, OpenAI). Focused on scalable architecture, clean code and quality.
.----------------------. | Ángel H. Barreiro | | full-stack dev | .____. |---------------------| | __ ) | hair: ~~~~~~~ | | _ \ | face: ( ^_^) | | |_) | | stack: {PHP, JS} | |____/ | SaaS · Symfony | '---------------------'
Experience
Full-stack developer with 6+ years building and shipping production SaaS. Backend with Symfony/PHP and API Platform, frontend with React/Next.js and TypeScript, and applied AI (RAG, OpenAI). Focused on scalable architecture, clean code and quality: from API design to delivery and real-user support.
Maintenance of a production ERP for a technical-services company and the design and implementation of its full-stack migration (Symfony/API Platform + Next.js).
Modernized a legacy system into a backend architecture with PHP/Symfony; developed and maintained REST APIs and core services.
Multi-tenant electronic-invoicing SaaS platform with Veri*factu/AEAT compliance; distributed architecture with a compliance microservice.
Development of headless solutions combining WordPress and Symfony.
Multilingual e-commerce management (PrestaShop) and collaboration with payment/logistics areas.
Contributions last year
1,706
Commits, PRs and private activity on GitHub
Repositories analysed
35
Private portfolio across SaaS, tooling and documentation
Active repositories
9
Projects under maintenance with an active roadmap
Repositories with stars
3
Highlighted repos with community feedback
Account created
April 2024
Since April 2024 contributing to open/private projects
Founderz · 2026
Master's program in Artificial Intelligence and Innovation applied to business.
Harvard University · 2025
Computer science and programming fundamentals: C, Python, SQL, algorithms and data structures.
Zend · 2025
Advanced program on object-oriented design patterns applied in PHP.
Core stack
Overview based on the analysis of 35 private repositories and recent contributions. Highlights technologies with the highest adoption, experience years and current focus on intelligent automation.
Relative share per language across analysed repositories
Annual contributions
1,706 private commits & PRs
Active repositories
9 repos under ongoing maintenance
🛠️ Backend
6+ yearsERP-to-SaaS migrations, REST APIs and service platforms with a focus on resilience and business domain expertise.
🛠️ Backend
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🎨 Frontend
5+ yearsEnterprise interfaces with Next.js 15/React 19, bespoke components and performance tuning.
🎨 Frontend
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🤝 Leadership & Communication
5+ yearsTeam management, stakeholder communication and effective incident resolution.
🤝 Leadership & Communication
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🗄️ Databases
5+ yearsModelling and optimization for high-availability systems with reporting and ETL.
🗄️ Databases
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⚙️ DevOps & Cloud
5+ yearsDeployment automation, infrastructure as code and observability for SaaS.
⚙️ DevOps & Cloud
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🤖 AI & Automation
3+ yearsModel integrations and intelligent workflow orchestration for process automation.
🤖 AI & Automation
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✅ Testing & QA
5+ yearsComprehensive coverage with unit, integration and end-to-end suites for continuous quality.
✅ Testing & QA
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Selection of SaaS products, internal tools and technical documentation created in professional projects. Organized into 6 strategic categories.
Billing & Compliance
Fiscal solutions and technical documentation for VeriFactu and ERP environments.
Service Management
SaaS applications to automate bookings, operations and back-office processes.
Advanced Architecture
Platforms focused on hexagonal architecture, DDD and scalability.
ERP & Digital Transformation
Modernizing legacy systems into maintainable SaaS infrastructures.
Tools & Automation
Internal products for analytics, automation and intelligent support.
Education & Community
Training material and technical challenges to share knowledge.
AI & Chatbots
Conversational assistants and RAG systems powered by generative AI.
Web app (Flask + SQLite) that automates recurring monthly maintenance for freelance clients: secure auth, client CRUD, plan-based dynamic checklists (Basic/Business/Critical), month-to-month navigation and a progress dashboard. CS50x final project, in real use.
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Multi-tenant SaaS platform for business management and electronic invoicing for freelancers and SMEs, fully compliant with Spain's Veri*factu / AEAT regulation. Distributed architecture: a management app (invoices, quotes, delivery notes and clients) on a database-per-tenant model, plus a standalone microservice that handles tax registration with the Spanish Tax Agency (hash chaining, XAdES digital signatures and SOAP communication). Includes Stripe subscription billing, plan-based feature gating and self-service onboarding. Live in production with real businesses.
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Following a critical local server failure that corrupted backups in 2021/2022, I took over the legacy code. Led data recovery and built a new corporate system from scratch using MVC architecture and modern paradigms.
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Maintenance and evolution of the production ERP of a technical-services company (repair orders, incidents and billing), plus the design and implementation of its full-stack migration to a modern architecture: a Symfony 7.3 + API Platform REST API and a Next.js 15 SPA. The migration was built as a standalone project and paused by the client's business decision.
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Maintenance and development of a React-based B2B platform with complex Web Services integration for Prestashop. Technical coordination with logistics and payment teams to resolve operational incidents.
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Have a project in mind? Let's talk