Available for freelance & contract engagements

Antonio Casado
Senior Backend Developer, Microservices, Kafka, AI, Kubernetes Engineer

Backend engineer with 17+ years building reliable, scalable systems for banking, finance, e-commerce and logistics — from technical design through deployment, monitoring, and production support.

Zürich, Switzerland 17+ years experience Freelance since 2024

Antonio Casado

Senior Backend Developer, Microservices, Kafka, AI, Kubernetes Engineer

17+YEARS EXPERIENCE
7COMPANIES & ENGAGEMENTS
3LANGUAGES SPOKEN
14+CERTS & COURSES
JavaSpring BootKafkaMicroservicesKubernetesPostgreSQLPythonAI
About

Engineering reliable systems for mission-critical environments

Senior Backend Developer with over 17 years of experience designing, developing, and operating enterprise backend systems across banking, finance, e-commerce, logistics, and data integration environments.

Deep hands-on expertise in Java, Spring Boot, microservices, REST APIs, Kafka, and event-driven architecture, combined with strong CI/CD, database, and observability skills across Oracle, PostgreSQL, Docker, and Kubernetes.

Experienced in building reliable, scalable backend services for mission-critical financial systems — from initial technical design through implementation, testing, deployment, monitoring, and operational support — while working closely with Product Owners, DevOps, QA, and cross-functional Scrum teams.

Architecture & DesignMicroservices, service decomposition, API design, EDA, DDD
Full SDLC OwnershipDesign, implementation, testing, deployment, production support
Data & PersistenceOracle, PostgreSQL, PL/SQL migration, SQL optimization
Quality EngineeringTDD, JUnit, Mockito, Testcontainers, clean code

LANGUAGES

English
Full Professional
Spanish
Full Professional (Native)
German
Medium Proficiency
Career Path

Work Experience

Seven engagements spanning banking, e-commerce, telecom, automotive and enterprise software — building backend systems that scale.

Freelance Software Engineer

03/2024 – Present
Self-Employed (Kode-Bytes)
Zürich · Finance, Logistics, Telecom
JavaSpring BootKafkaPythonPostgreSQLDockerKubernetesGitLab CIFlinkSparkDatabricks
  • Designed enterprise backend and data-integration services using Java, Spring Boot, Kafka, PostgreSQL, Docker and Kubernetes.
  • Built microservice components for processing, validating, transforming and persisting data for downstream consumers.
  • Contributed to technical design decisions on service boundaries, integration flows and operational resilience.
  • Developed Python automation for data validation, ETL-style workflows and integration testing.
  • Diagnosed performance bottlenecks in Docker/Kubernetes workloads, improving latency and throughput.
  • Enforced unit test coverage and code quality through reviews and development guidelines.

Senior Software Engineer

05/2022 – 12/2023
EPAM
Zürich · Banking
Java 11/8Spring BootSpring SecurityKafkaOracle PL/SQLPostgreSQLAzureELKMongoDBSpark
  • Designed and evolved event-driven microservices for banking platforms with a focus on data correctness and reliability.
  • Defined RESTful API contracts using OpenAPI and established service-level design principles.
  • Led migration from Oracle PL/SQL to PostgreSQL, rewriting stored procedures and optimizing complex queries.
  • Collaborated with Product Owners, data engineers, QA and DevOps across the full SDLC in regulated banking environments.

Senior Software Engineer

12/2020 – 05/2022
Ippen-Digital
Munich · Customer Data Platform
Java 15Spring BootKafkaRabbitMQFlinkPythonSpring GraphQLELKDDDReact
  • Built a real-time customer data platform ingesting, enriching and distributing data to downstream systems.
  • Designed REST and GraphQL APIs and applied Domain-Driven Design to improve service boundaries and modularity.
  • Implemented Kafka-based integration flows for asynchronous, event-driven data processing.
  • Used Python for automation, data transformation utilities and pipeline-related tasks.

Senior Software Engineer

06/2018 – 08/2020
Intelligenia
Stuttgart · B2B E-commerce
Java 8Spring Boot/CloudSpring GraphQLOAuth2KafkaDockerSQL ServerELK
  • Refactored legacy monolithic applications into Spring Boot microservices with clearly defined service boundaries.
  • Implemented secure backend services using Spring Security, OAuth2 and OpenID Connect.
  • Improved maintainability by separating business logic, integration and persistence concerns.

Senior Software Engineer

02/2018 – 06/2018
IC-Consult
Stuttgart · IAM (Daimler)
JEE7WebSphereSpring Boot
  • Delivered backend components for a web-based IAM solution in an enterprise environment.
  • Ensured code quality, documentation and alignment with enterprise development standards.

Senior Software Engineer

01/2016 – 01/2018
Deutsche Automobil Treuhand
Ostfildern-Stuttgart
Java 8JavaScriptjQueryRESTSOAPJettyGrizzlyMavenJenkins
  • Introduced asynchronous REST interfaces to replace legacy SOAP flows, significantly uplifting performance.
  • Developed a Web-Scan REST service enabling automated data retrieval from external sources.

Software Engineer

08/2014 – 08/2015
SIEMENS Polarion
Stuttgart · ALM
Java 8JavaScriptjQueryRESTSOAPJenkins
  • Delivered features for Polarion ALM and designed PolarionNEXT, a microservices-based ALM platform.
  • Streamlined software delivery processes using Scrum, Agile and SDLC methodologies.
Academic Background

Education

Master's Degree in Communications and Technology Management

1996
EOI Business School
Madrid

Bachelor's Degree in Computer Science

1990 – 1996
Software Development & Artificial Intelligence
Granada
Technical Toolkit

Skills & Technologies

A grounded, production-tested stack built across banking, e-commerce and data-integration systems.

Languages & Frameworks

Java 8/11/17/21Spring BootSpring DataSpring SecuritySpring CloudHibernateJPAPython

APIs & Architecture

RESTGraphQLSOAPOpenAPIOAuth2OpenID ConnectMicroservicesDDD

Event-Driven & Streaming

KafkaKafka StreamsRabbitMQJMSFlinkSparkDatabricks

Databases & Persistence

OraclePostgreSQLPL/SQLSQL ServerMongoDBSQL Optimization

DevOps & Cloud

DockerKubernetesHelmJenkinsGitLab CIMavenGradleAzure

Observability & Quality

GrafanaPrometheusMicrometerELKOpenTelemetryJUnitMockitoTestcontainersTDD
Writing

Publications

Technical articles sharing hands-on insight from real backend engineering work.

Article

Spring AI

Exploring how Spring AI brings AI-powered capabilities into the Spring ecosystem for backend developers.

October 2025
Article

Dockerizing Spring Boot Applications

Comparing different ways to build and package Spring Boot applications as Docker images.

September 2024
Article

Java Records vs Lombok

How Java Records improve everyday coding compared to traditional Lombok-generated boilerplate.

June 2024
Continuous Learning

Certifications & Courses

Ongoing professional development across cloud, data and distributed systems.

Databricks for Data Analysts

LinkedIn · 06/2026

Data Modeling in MongoDB

LinkedIn · 10/2025

GraphQL for Enterprise Developers

LinkedIn · 10/2025

Azure Kubernetes Service (AKS) — Deploying Microservices

LinkedIn · 09/2025

Azure Cloud Fundamentals: Cloud Services

LinkedIn · 08/2025

Kafka on Kubernetes

LinkedIn · 04/2025

Docker Compose

LinkedIn · 04/2025

Microsoft Azure (AZ-900) Cert Prep: Cloud Concepts

LinkedIn · 11/2022

Agile Foundations

LinkedIn · 05/2022

Extending, Securing & Dockerizing Spring Boot Microservices

LinkedIn · 05/2022

Kubernetes

LinkedIn · 05/2022

Apache Kafka: Designing Event-Driven Applications

Pluralsight · 07/2019

Distributed Programming in Java

Rice University · Coursera · 01/2018

Mastering Microservices with Java

LinkedIn · 01/2018

Machine Learning

Stanford University · Coursera · 11/2016

Let's build something reliable together

Open to freelance and contract engagements in backend engineering, microservices architecture, and event-driven systems.

Quick Facts

LocationZürich, Switzerland
StatusFreelance / Contract
FocusJava · Spring Boot · Kafka
LanguagesEN · ES · DE
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