Robert is available for hire
Hire RobertRobert Deak
Verified Expert in Engineering
React and Node.js Developer
Zagreb, Croatia
Toptal member since January 29, 2019
Bio
Robert is a software architect and developer with 10+ years of engineering experience, specializing in React and Node.js for the past four years. While building efficient, maintainable, and fault-tolerant apps, he has worked on every phase of software development, including product user stories, development, testing, and CI/CD pipelines. Robert excels at delivering what clients need and want.
Portfolio
Pfizer - PGS Operations Insights
JavaScript, CSS, HTML, Node.js, React, GraphQL, Docker, Neo4j, REST APIs...
Tom Hayford
JavaScript, React, Node.js, PostgreSQL, APIs, SQL, Neo4j, Terraform, AWS IoT...
M3G Technology
React, WebSockets, REST, Webpack, Styled-components, TypeScript...
Experience
- Integration - 10 years
- Oracle PL/SQL - 10 years
- Spring - 8 years
- Java - 8 years
- JavaScript - 5 years
- React - 4 years
- Node.js - 4 years
- TypeScript - 3 years
Preferred Environment
JetBrains IDE
The most amazing...
...thing I did was productize ML models to automate complex decisions at scale, saving the business millions in operational costs.
Work Experience
Full-stack Developer
2022 - PRESENT
Pfizer - PGS Operations Insights
- Productized over a dozen machine learning models, driving multimillion-dollar cost reductions by automating complex decision-making processes at scale.
- Contributed to the development of a federated search engine with Google-like capabilities, delivering fast, seamless data retrieval across diverse and heterogeneous data sources.
- Architected and delivered a specialized molecular feasibility tracking application with integrated data visualizations that accelerated chemistry research workflows, significantly reducing brainstorming cycle times among research teams.
- Created an OLAP-based employee training tracking system, offering real-time insights into curriculum completion rates and improving department compliance.
- Engineered a dynamic workforce allocation system that optimizes employee assignment distribution across multiple divisions based on real-time availability, improving operational efficiency and resource utilization.
- Built a dynamic data exploration platform that allows users to map, sort, filter, and customize views of datasets in real time, enhancing data accessibility and user autonomy.
- Developed data streaming API capable of generating and streaming large-scale documents, ensuring reliable delivery and low-latency performance under heavy load.
- Built advanced interactive data visualizations, empowering stakeholders to explore complex datasets intuitively and make data-driven decisions faster.
- Designed and implemented a robust Role-based Access Control (RBAC) system, enhancing platform security and enabling fine-grained user permissions management.
Technologies: JavaScript, CSS, HTML, Node.js, React, GraphQL, Docker, Neo4j, REST APIs, Python, FastAPI, PostgreSQL, Elasticsearch, D3.js, Pandas, Gurobi
Full-stack React/Node.js Developer
2024 - 2024
Tom Hayford
- Architected and launched a greenfield project from inception to production, establishing a scalable and maintainable foundation for future development.
- Designed and implemented infrastructure as code (IaC) using Terraform to automate AWS provisioning, enabling repeatable, version-controlled environment management.
- Built an end-to-end CI/CD pipeline with GitHub Actions, accelerating deployment workflows and shortening release cycles.
- Developed an optimized data architecture for material flow and inter-component integration, enabling users to complete equivalent work several months faster.
Technologies: JavaScript, React, Node.js, PostgreSQL, APIs, SQL, Neo4j, Terraform, AWS IoT, Next.js
Senior React Architect | Developer
2021 - 2022
M3G Technology
- Built a responsive front-end application that enables seamless customer communication through SMS.
- Translated full UI designs into modular, reusable React components focusing on performance, including image optimization.
- Integrated real-time messaging via WebSocket alongside REST API endpoints to ensure a reliable communication flow.
- Troubleshot and resolved critical issues in a legacy Angular codebase, improving stability and maintainability.
- Took initiative in laying the groundwork for a real-time user notification system to enhance user engagement.
Technologies: React, WebSockets, REST, Webpack, Styled-components, TypeScript, User Interface (UI), Unit Testing, HTML, GitHub, CSS, Jira, Web API, Web Notifications, HTML5, Event Design, REST APIs
Senior React Developer
2021 - 2021
iContainers
- Set up a full-featured development environment from scratch, following best practices—covering build tooling, linting, testing, Storybook, tracing, error handling, and project structure.
- Transformed dozens of Figma designs into well-structured, reusable React components, ensuring visual accuracy and responsive behavior.
- Migrated and refactored an entire component library to TypeScript, improving type safety, maintainability, and developer productivity.
- Streamlined the GitLab CI/CD pipeline for faster, more reliable deployments and introduced automated changelog generation to improve release transparency.
- Strengthened the testing strategy by enhancing coverage and implementing end-to-end testing with Cypress.io for critical user flows.
- Integrated a wide range of core REST API endpoints to power essential business functionality and ensure seamless data flow across the application.
Technologies: TypeScript, React, React Redux, API Integration, Jest, Figma, HTML, CSS, Sentry, GitLab, Release Management, Private NPM Modules, Material UI, React Query, React Hook Form, Storybook, ESLint, ParcelJS, Cypress, REST, OpenAPI, Localization, React Router, Unit Testing, HTML5, REST APIs
React Architect and Developer
2021 - 2021
IntelliQuit
- Set up a Next.js project with testing, linting, and a streamlined deployment workflow.
- Translated Figma designs into responsive, pixel-perfect UIs for both mobile and desktop.
- Applied an OpenCV algorithm to validate image content on the client side before uploading.
- Integrated Google Analytics and user tracking to monitor engagement and behavior.
- Developed a REST API for processing and managing nicotine test image submissions.
Technologies: React, Next.js, REST, OpenCV, Figma, Google Analytics, API Integration, User Interface (UI), HTML, CSS, GitHub, HTML5, REST APIs
Senior Full-stack React and Node.js Developer
2019 - 2021
Agility Logistics (via Toptal)
- Contributed to the refactoring and redesigning of a large React application for improved performance and maintainability.
- Developed key back-end features in Node.js and TypeScript, aligning with core business requirements.
- Built and integrated a complex multi-step form in React with dynamic, interdependent fields for quoting and booking workflows.
- Helped containerize the application and its dependencies using Docker for streamlined development and deployment.
- Set up and maintained end-to-end tests with Cypress.io, integrated them into CI, and authored extensive test coverage.
- Integrated external freight APIs to enable seamless third-party data exchange.
- Implemented GraphQL resolvers with Redis caching for long-term data storage and fast response times.
- Built reusable MongoDB repositories using Node.js and TypeScript for cleaner data access patterns.
- Migrated significant business logic from legacy PL/SQL to a modern Node.js service architecture.
Technologies: React Redux, JavaScript, Agile, SQL, Oracle SQL, GitFlow, Oracle PL/SQL, CircleCI, Docker Compose, Docker, API Integration, Jest, Cypress, Styled-components, Figma, Express.js, Apollo Server, React Apollo, GraphQL, Redux, MongoDB, Node.js, React, TypeScript, Redis, Material UI, PL/SQL, Sagas, Redux-Saga, Apollo, React Router, Kibana, Full-stack, User Interface (UI), HTML, CSS, Unit Testing, Atomic Design, Amazon Web Services (AWS), Meteor, Redis Queue, Message Queues
Senior React Developer (via Toptal)
2020 - 2020
M3G Technology
- Fixed issues by styling Stripe components and wrapping them in Material UI components.
- Aligned a custom React build with a Django app’s deployment flow by resolving asset bundling issues.
- Refactored and streamlined the codebase, removing nearly 30% of redundant code and unused libraries to improve performance and maintainability.
Technologies: React, Stripe, Stripe API, Material UI, Axios, React Router, HTML5
React Architect and Developer
2019 - 2019
Battery Learning, Inc. (via Toptal)
- Defined the front-end and back-end project structure.
- Built a custom, Medium-like, Draft.js editor in React.
- Implemented Firebase Authentication, Cloud Firestore, and firestorage functionalities.
- Created a SCORM generator (2004 third Edition) in Node.js.
- Set up the Apollo Client and Apollo cache as local storage instead of Redux.
Technologies: Express.js, JavaScript, GitFlow, Draft.js, SCORM, Firebase, GraphQL, Node.js, React, Apollo, React Apollo, HTML, CSS, GitHub, HTML5
TypeScript Developer
2019 - 2019
Rockpapr
- Integrated the Xero API, Stripe API, and NetSuite (Node.js).
- Implemented the entire user onboarding process using React.
- Dockerized Node.js and React applications with all the dependent services.
Technologies: React Redux, JavaScript, SQL, Oracle SQL, GitFlow, SuiteScript 1, NetSuite, Xero API, Stripe API, Docker, Express.js, Node.js, TypeScript, React, Stripe, REST APIs
Senior Java Architect
2009 - 2019
Privredna Banka Zagreb, Intesa Sanpaolo Group
- Designed and implemented a highly scalable messaging service.
- Created and implemented several key features into a branch application for corporate clients.
- Implemented and designed payment processing into an internet banking application.
- Developed several large batch processes into a retail back-end application.
- Constructed and implemented an application for processing standing orders.
- Served on a team focused on integrating PBZ banking solutions with other banks in the Intesa Sanpaolo Group.
Technologies: React Redux, Spring Microservice, Spring MVC, Agile, SQL, Oracle SQL, GitFlow, Oracle PL/SQL, Java Message Service (JMS), IBM WebSphere, TypeScript, Angular, React, JavaScript, Jakarta Server Pages (JSP), Spring, Java, Oracle, Spring Boot, Oracle RDBMS, Agile Sprints, Spring JDBC, Spring REST, Spring Data REST, Full-stack, Swagger, Jira, IBM MQ, Message Queues
Front-end Developer
2008 - 2009
Siemens
- Implemented several specific UI components for the Advantage platform.
- Created a tool for tracking component releases and creating a changelog.
- Assisted with integration testing for several internal systems.
Technologies: Agile, GitFlow, IBM Rational ClearCase, JavaScript, Jakarta Server Pages (JSP), Java
Back-end Developer
2006 - 2008
Dialog
- Created a B2B portal for a local brush factory using Apex.
- Implemented a reporting module for a betting web application.
- Designed and implemented a salary module within a custom ERP solution.
Technologies: JavaScript, SQL, Apex, Oracle Reports, Oracle Forms, Oracle PL/SQL, Oracle SQL
Lead Web Developer
2002 - 2004
Osijek-Online
- Created an eCommerce platform for clients to place orders and track records.
- Built a ticket reservation platform for a Croatian national theater in Osijek, Croatia.
- Constructed a content management platform for a local news portal.
Technologies: SQL, CSS, HTML, jQuery, JavaScript, PHP
Experience
Our Family Chef
A React application that tracks eating habits and assists in making weekly menus and shopping lists. The user enters the meals they plan to make during the week and their ingredients, and the application tries to balance the menu by ingredient type.
OLTP SQL Optimization in a Retail Banking Application
The application was unresponsive when a user requested a transaction list or account details. I reduced response time from more than five seconds to around 300 milliseconds by identifying and dropping all the unused indexes and rewriting critical SQLs.
Digital Certificate Issuing Service
An Angular application I developed for issuing digital certificates to bank clients. In addition to designing and implementing the application, I integrated it with a certification authority over SOAP services.
Customer Call Center Authorization Service
Banks need additional authorization after a customer enters a recipient account that hasn't been used before. I designed and implemented an authorization service that enables bank officers to identify callers using their personal information.
Billing Application
A billing application I created to enable users to configure a list of services and subscription models using event sourcing. Services can be grouped in a package and offered as a subscription model. Users can also mark a service as free of charge or provide a discount for all users or specific users.
E-invoice Service
A service I designed, developed, and integrated with internet banking. After a user receives an e-invoice within an internet banking platform, they can review it and decide whether to accept or reject it.
Education
1998 - 2002
Master's Degree in Financial Management
Josip Juraj Strossmayer University of Osijek, Faculty of Economics - Osijek, Croatia
Certifications
FEBRUARY 2023 - FEBRUARY 2026
AWS Certified Developer – Associate
Amazon Web Services
AUGUST 2021 - PRESENT
Toptal React Academy Graduate
Toptal, LLC
FEBRUARY 2016 - PRESENT
Oracle Advanced PL/SQL Developer Certified Professional
Oracle
AUGUST 2013 - PRESENT
Oracle Database 11g: Program with PL/SQL
Oracle
DECEMBER 2012 - PRESENT
Oracle Database SQL Certified Expert
Oracle
JUNE 2012 - PRESENT
ITIL V3 Foundation
Exin
Skills
Libraries/APIs
React, Node.js, React Redux, Redux Form, RxJS, Spring REST, Redux-Saga, jQuery, Java Message Service (JMS), Xero API, Stripe, Stripe API, OpenCV, React Query, React Hook Form, OpenAPI, React Router, Redis Queue, Web API, REST APIs, D3.js, Pandas
Tools
GitHub, Apache Maven, Docker Compose, Redux Thunk, React Apollo, Figma, CircleCI, Oracle Forms, Oracle Reports, IBM Rational ClearCase, Git, Sentry, GitLab, Google Analytics, Webpack, Kibana, Jira, IBM MQ, Terraform, Gurobi
Languages
HTML, Java, SQL, JavaScript, TypeScript, GraphQL, CSS, PHP, Apex, SuiteScript 1, HTML5, Python
Frameworks
Express.js, Spring Boot, Redux, Spring MVC, Spring Microservice, Spring, Next.js, Angular, Spring JDBC, Hibernate, Cypress, Jest, Jakarta Server Pages (JSP), Draft.js, Material UI, Swagger
Paradigms
REST, Agile, Unit Testing, SCORM, Event Sourcing
Platforms
Oracle, Docker, IBM WebSphere, Firebase, Amazon Web Services (AWS), Meteor, AWS Lambda, AWS IoT
Storage
Oracle SQL, Oracle PL/SQL, Spring Data, Spring Data JPA, MongoDB, Oracle RDBMS, PostgreSQL, Redis, PL/SQL, Spring Data REST, OLTP, Amazon DynamoDB, Neo4j, Elasticsearch
Other
GitFlow, APIs, Integration, Full-stack, Micro SOA, Atomic Design, JetBrains IDE, Apollo Server, Styled-components, API Integration, NetSuite, Sagas, Release Management, Private NPM Modules, Storybook, ESLint, ParcelJS, Localization, Apollo, WebSockets, Axios, Agile Sprints, Financial Management, ITIL V3 Foundation Certified, SOAP, Authorization, Billing Software, Subscriptions, Online Banking, User Interface (UI), Message Queues, Web Notifications, Event Design, Amazon API Gateway, FastAPI
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