Attila Fejér, Developer in Budapest, Hungary
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Attila Fejér

Verified Expert  in Engineering

Architectural Design Developer

Budapest, Hungary
Toptal Member Since
October 16, 2019

Attila is a seasoned software engineer with several years of experience under his belt. He has expertise in the Spring Framework and the Java ecosystem and robust skills regarding front-end technologies, DevOps, architectural design, and object-oriented programming. Attila has led development teams ranging from 4 to 10 members, is dedicated to continuous growth, and has created and taught several development courses.


Java, JavaScript, TypeScript, Spring, Docker, Angular, Architecture, Coaching...
CyClick Kft.
Liquibase, Bootstrap, JavaScript, Java EE, Java, MySQL, REST APIs, Java 8, SQL...
Apertus Nonprofit Kft.
NGINX, Hazelcast, Jenkins, MySQL, Spring, Java, REST APIs, JavaScript...




Preferred Environment

Git, Visual Studio Code (VS Code), IntelliJ IDEA, Java, Spring Boot, JavaScript, Linux, Containers, REST APIs

The most amazing...

...performance improvement I've reached was decreasing a REST API's under-load response time from 90 seconds to 30 milliseconds using sophisticated caching.

Work Experience

Software Engineer

2020 - 2024
  • Designed and implemented highly scalable software products in a cloud environment.
  • Mentored, trained, and coached people and teams in applying software development best practices and adopting new internal tooling.
  • Led training programs that impacted 10,000+ developers.
Technologies: Java, JavaScript, TypeScript, Spring, Docker, Angular, Architecture, Coaching, Team Mentoring

Full-stack Developer

2019 - 2019
CyClick Kft.
  • Created an event organizing administrative module to an existing ERP system.
  • Ported various features from a Java Swing application to a web application.
  • Contributed to every part of the project, from requirements gathering to application deployment.
  • Introduced database change management using Liquibase.
  • Optimized the Jakarta EE server code performance on WildFly.
Technologies: Liquibase, Bootstrap, JavaScript, Java EE, Java, MySQL, REST APIs, Java 8, SQL, JUnit, Git, AssertJ, TypeScript, Linux

Lead Software Developer

2017 - 2019
Apertus Nonprofit Kft.
  • Wrote Spring Boot code using IntelliJ IDEA.
  • Unified Jenkins build and deploy pipelines.
  • Strengthened development methodologies by introducing unit testing and TDD.
  • Assessed under-performing software and identified ways that it could be improved.
  • Collaborated on all stages of system development lifecycles, from requirements gathering to production releases.
  • Designed the system architecture and integration points between loosely coupled back-end applications.
Technologies: NGINX, Hazelcast, Jenkins, MySQL, Spring, Java, REST APIs, JavaScript, Hibernate, Java 8, Spring Boot, SQL, JUnit, Git, AssertJ, TypeScript, Linux, JBoss


2014 - 2017
Freelance Work
  • Taught an assortment of programming courses concerning Java-related technologies and programming theory.
  • Consulted with the clients about the course curriculum.
  • Created course materials with real-world examples.
  • Assessed client workflows and methodologies to customize training material.
  • Prepared and executed exams to measure the students' performance.
Technologies: Apache Maven, GWT, JPA, Spring, Android, Java EE, Java, REST APIs, JavaScript, Spring Boot, SQL, JUnit, Git, AssertJ, TypeScript

Co-founder | CEO | Software Engineer

2012 - 2015
Just Another Company Kft.
  • Delivered projects while meeting the predetermined budget, time parameters, and quality standards.
  • Applied strong leadership talents and problem-solving skills to maintain team efficiency and organize workflows to meet any daily demand.
  • Worked closely with clients to establish problem specifications and system design.
  • Evaluated project requirements and specifications.
  • Developed applications that surpassed client expectations.
  • Wrote Java, Java EE, GWT, and C# code.
Technologies: MySQL, C#, GWT, Java EE, Java, JavaScript, Spring Boot, SQL, JUnit, Git, AssertJ, Linux, JBoss

Ride Balaton

It's an online off-track bicycle tour planner platform with manual and automatic route planning. The related Android application has navigation capabilities.

ERP System

It's a multipurpose ERP system with modules like stock management, calendar, document management, billing, ticketing, reporting, todo management, project planning, and POS.

Author at

I frequently publish articles about Java-based technologies.
2012 - 2015

Master of Science Degree in Electrical Engineering

Budapest University of Technology and Economics - Budapest, Hungary

2008 - 2012

Bachelor of Science Degree in Computer Engineering

Budapest University of Technology and Economics - Budapest, Hungary


Oracle Certified Professional Java 8 Developer


MAY 2017 - MAY 2020

Google Certified Associate Android Developer



JPA 2, Lombok, AssertJ, REST APIs, Liquibase


MapStruct, Eclipse IDE, IntelliJ IDEA, Apache Maven, Gradle, Git, NGINX, WildFly, Google Compute Engine (GCE), Jenkins, GitLab, GitLab CI/CD, GitHub


Spring, Spring Boot, Hibernate, JUnit, Mockito, GWT, Bootstrap, JPA, Angular


Java EE, Eclipse, Visual Studio Code (VS Code), Android, Linux, Amazon Web Services (AWS), Docker, JBoss


Java 8, Java, JavaScript, TypeScript, SQL, C#


MySQL, MongoDB, Hazelcast


AOP, Object-relational Mapping (ORM), Design Patterns, Unit Testing, Functional Programming, Test-driven Development (TDD)


OOP Designs, Architectural Design, Containers, Architecture, Coaching, Team Mentoring

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