Ondrej Kuzmik, Developer in Bratislava, Bratislava Region, Slovakia
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Ondrej Kuzmik

Verified Expert  in Engineering

Back-end Developer

Bratislava, Bratislava Region, Slovakia
Toptal Member Since
March 29, 2022

Ondrej is a seasoned back-end developer who enjoys solving technological problems or challenges requiring logical thinking like designing new software architecture, participating in programming competitions, or playing chess. During his career, Ondrej has held various positions ranging from junior developer to team leader or software architect. Skilled in different technologies, programming languages, and frameworks, his preference and main expertise lie in solving back-end-related tasks.


Product Design, Amazon Web Services (AWS), Architecture, GraphQL, Microservices...
Ohpen Foundation
Amazon Web Services (AWS), Java, Spring Boot, AWS Lambda, OpenAPI, REST...
Davinci Software
Amazon Web Services (AWS), Java, Spring Boot, Amazon DynamoDB...




Preferred Environment

Amazon Web Services (AWS), Java, IntelliJ IDEA, Spring Boot

The most amazing...

...thing I've done was to keep calm and fix a huge data inconsistency incident on production that affected different teams.

Work Experience

Teach Lead

2021 - PRESENT
  • Helped the client design a new finance product and pick the best SaaS partners.
  • Jumped on an existing project and quickly prepared it for production.
  • Handled high-level architecture and estimates for projects still in the discovery phase.
  • Architected and team-led the project, where the scope was to develop a mobile application for credit cards, specifically onboarding, 3DS, transactions, and repayments.
  • Integrated the app with the existing solution focused on different product types.
  • Implemented a green field mobile application for managing investment portfolios. Developed a web portal for internal users.
Technologies: Product Design, Amazon Web Services (AWS), Architecture, GraphQL, Microservices, REST, Apache Kafka, Terraform, AWS Step Functions, Java, Kotlin, DevOps, APIs, Spring Boot

Software Architect

2020 - 2021
Ohpen Foundation
  • Worked as one of the company architects. Oversaw a project in handling consumer loans (mid-office) and also other smaller ones.
  • Supported several teams by solving more complex technical tasks and architectural guidance in projects using new technologies, e.g., serverless.
  • Led one of the projects until significantly improved the project reliability.
  • Held one-to-one performance meetings with several team members twice a year. Used them to improve a colleague's performance, helping him become a successful team leader.
Technologies: Amazon Web Services (AWS), Java, Spring Boot, AWS Lambda, OpenAPI, REST, Microservices

Team Leader

2014 - 2020
Davinci Software
  • Held one-on-one performance meetings with the team members.
  • Led the move from on-premise to AWS and to cloud-native architecture for the corresponding service.
  • Progressed to a software architect role to support other teams with the move to AWS and other new technologies.
Technologies: Amazon Web Services (AWS), Java, Spring Boot, Amazon DynamoDB, Amazon Simple Queue Service (SQS), REST, Microservices


A project to transform optical character recognition (OCR) results into humanly readable forms, for example, parsing data, ID documents, or salary slips.

I included features like repairing data using UI, custom response structures for different customers, or validation of extracted data. It was also composed of several smaller services responsible for other tasks like validation, virus scanning, or OCR results transformation. Later on, there were also serverless components added.


Java, GraphQL, Kotlin


Spring Boot, Spring


Amazon Simple Queue Service (SQS), Amazon Cognito, Terraform, AWS Step Functions


Microservices, DevOps, REST


Back-end, Infrastructure as Code (IaC), Team Leadership, Software Architecture, APIs, Product Design, Serverless, Architecture




Amazon Web Services (AWS), Apache Kafka, AWS Lambda


Amazon DynamoDB, PostgreSQL, NoSQL

2009 - 2014

Master's Degree in Computer Science

Slovak University of Technology - Bratislava, Slovakia