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Clean Code & Microservices

Senior Backend Developer specializing in Java, Kotlin, and Spring Boot. I build scalable microservices and global data platforms.

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About me

developer_profile.kt
fun getSeniorBackendEngineer(): SeniorBackendEngineer = SeniorBackendEngineer(
  fullName = "Abel Deltell Alfonso",
  alias = "abdeal",
  experienceYears = 10,
  languages = listOf("Java", "Kotlin"),
  consultancies = listOf("Hiberus", "Experis", "Altia", "Everis"),
  endClients = listOf("Mango", "Inditex (Zara)", "Santander", "WIPO", "Telefónica"),
  active = true
)

I am ABel DEltell ALfonso (abdeal), a software engineer with over 10 years of experience specialized in the backend ecosystem. Over the past decade, I have solidified deep expertise in Java and Kotlin, designing clean architectures, scalable microservices, and decoupled high-concurrency systems.

Throughout my career, I have worked at industry-leading consultancies including Hiberus, Experis, Altia, and Everis (NTT DATA), delivering strategic projects for major global brands: from the core shopping cart and checkout platform at Inditex (Zara), financial and insurance integrations with Banco Santander, Mutua Madrileña, and FIRA Barcelona, to international platforms for the WIPO / OMPI, telecommunications with Telefónica, and transversal analytics platforms at Mango.

Beyond the backend, I am deeply enthusiastic about modern frontend technologies and Artificial Intelligence (LLMs and autonomous agent architectures), blending these disciplines to build and launch complete, end-to-end applications that are 100% functional.

  • LocationSpain
  • FocusBackend Architecture
  • InterestsClean Code, Microservices, Data

Experience

CV
terminal://experience/hiberus
Dec 2022 - Present

Hiberus

(Mango)

> Senior Backend Engineer (Java / Kotlin)

Development in Data and Transversal SE teams at Mango, building global analytical platforms and high-availability systems.

// Responsibilities & Architecture:

Development of global analytical platforms, price optimization tools, and employee management systems using Spring Boot, MongoDB, RabbitMQ, and Apache Kafka. Implementation of Kafka topic producers and consumers, as well as configuration and deployment of Kafka Connectors for direct persistence (sink) into databases. Strict application of Clean Architecture, Domain-Driven Design (DDD), and rigorous testing.

terminal://experience/experis-spain
Sep 2021 - Dec 2022

Experis Spain

(Santander, FIRA Barcelona, Mutua Madrileña)

> Senior Backend Engineer (Java)

Large-scale RESTful integrations and microservices for banking, insurance, and massive events.

// Responsibilities & Architecture:

Developed and maintained large-scale Java microservices for top-tier clients (Banco Santander, Mutua Madrileña, FIRA Barcelona). Projects included API integrations for medical video consultation platforms and ticketing systems for high-concurrency massive events. Optimized database queries and asynchronous flows.

terminal://experience/altia
Jan 2019 - Sep 2021

Altia

(Inditex (Zara Checkout & Shopping Cart))

> Senior Backend Engineer (Java / Kotlin)

Critical development in Zara's core shopping cart and global Checkout gateway.

// Responsibilities & Architecture:

Developed within the core shopping cart and Zara's global Checkout platform. Applied fallback resilience patterns and international payment orchestration to withstand massive traffic spikes during Black Friday. Direct collaboration with product and frontend teams to optimize conversion rates.

terminal://experience/everis--ntt-data-
Feb 2016 - Dec 2018

Everis (NTT DATA)

(WIPO (World Intellectual Property Org) & Telefónica)

> Backend Engineer (Java)

Microservices architecture for WIPO (UN) and Telefónica telecommunication platforms.

// Responsibilities & Architecture:

Designed and developed microservices with Spring Cloud, Oracle, and Docker for international bodies such as WIPO/OMPI and major telecom operators (Telefónica). Modernized legacy architectures into decoupled microservices and CI/CD automation pipelines.

Tech Stack

Java
Kotlin
Spring Boot
Architecture & Systems (Clean Architecture, DDD)
RabbitMQ
Kafka
Docker / CI/CD (Jenkins, Helm)
Oracle
MongoDB
PostgreSQL
Couchbase
JavaScript / Frontend (Astro, React, Tailwind)

Featured Projects

# Personal Projects

https://joinclubflow.com/

Clubflow

Independently developed management platform.

ReactViteKotlinSpring BootTailwindCSS

# Professional Projects

adalytics-en.kt

Adalytics (Mango)

Global analytics platform for real-time KPIs, store sales, and footfall data, improving visibility and strategic planning.

KotlinSpring BootMicroservices
check-pay-en.kt

Check & Pay (Mango)

Salary management system used by HR teams across countries, integrated via RabbitMQ and Server-Sent Events (SSE).

JavaSpring BootRabbitMQ
zara-checkout-en.kt

Zara Checkout & Payment Pipeline (Inditex)

Mission-critical checkout module and payment orchestration platform (cards, gift cards, Klarna) leveraging reactive programming and resilience patterns for high-traffic events like Black Friday.

JavaSpring BootReactiveDockerKafkaGrafana
zara-cart-en.kt

Zara Shopping Cart Core & Adapters (Inditex)

Maintenance and development of microservices for Zara's core shopping cart and adapter layers communicating with frontend teams, featuring service mocking, high resilience, and low latency.

JavaSpring BootDockerMicroservicesREST APIs
wipo-everis-en.kt

WIPO Platform (Everis / World Intellectual Property Org)

Internal office microservices platform to manage international intellectual property submissions and licensing workflows. Included automated PDF generation, asynchronous RabbitMQ messaging, and BPM flows.

JavaSpring BootRabbitMQMicroservicesREST APIs
tele-consulting-en.kt

Tele-Consulting Platform (Mutua/Catalana)

Patient and customer management system supporting remote video consultations, improving healthcare accessibility.

JavaSpring BootREST APIsMicroservices

Latest Notes

View all posts

Launch of my new personal web space with Astro

Why I decided to migrate to Astro and how I set up a modern architecture without the need for a dedicated backend.

Get In Touch

Whether you have a project in mind or just want to say hi, my inbox is always open.