Aleksa Djurdjulov, Developer in Kikinda, Vojvodina, Serbia
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Aleksa Djurdjulov

Verified Expert  in Engineering

Bio

Aleksa is a full-stack developer who loves solving complex problems in simple ways. Focused on building web and mobile apps, he values user feedback and treats it as the main pointer when choosing what to create next. Aleksa is proficient in Kotlin, Spring Boot, React, and Flutter and pursues clean code and a test-driven development approach.

Portfolio

Yummy Ou
Kotlin, Spring Boot, Shopify, Shopify API, Shopify Storefront API, Klaviyo...
Vacuumlabs
Kotlin, Spring Boot, React, TypeScript, PostgreSQL, Back-end Development...
Gig-a Bank
Kotlin, Spring Boot, Flutter, PostgreSQL, Amazon Web Services (AWS)...

Experience

  • React - 5 years
  • TypeScript - 5 years
  • Kotlin - 5 years
  • Spring Boot - 5 years
  • Java - 3 years
  • Flutter - 2 years
  • Design Patterns - 2 years
  • Amazon Web Services (AWS) - 2 years

Availability

Full-time

Preferred Environment

Spring Boot, Kotlin, TypeScript, React, Flutter, Java

The most amazing...

...thing I've implemented is a custom name-searching system built in Elasticsearch that helps fight against money laundering.

Work Experience

Full-stack Developer

2023 - PRESENT
Yummy Ou
  • Optimized API logic and improved architecture by implementing retry mechanisms to reduce REST API error rates to 0.1%, which improved overall system stability and customer experience.
  • Migrated observability from CloudWatch to DataDog, improving insights and enabling faster troubleshooting. The migration led to significantly reduced error rates and quicker incident response times, ensuring reduced downtime for users.
  • Added multiple back-office features using Shopify Extensions, enabling admins to update and manage subscription details, modify recipes, and enforce rules, making the system more scalable and improving operational efficiency.
  • Migrated from Bold Subscriptions to native Shopify subscriptions, removing dependency on third-party services and improving subscription management, leading to better customer retention and satisfaction.
Technologies: Kotlin, Spring Boot, Shopify, Shopify API, Shopify Storefront API, Klaviyo, React, TypeScript, PostgreSQL, AWS IoT, Back-end Development, API Development, Architecture, Amazon Web Services (AWS), Back-end, Shopify Design, Shopify Liquid, Shopify Customizations, Shopify Scripts, shopify functions, Shopify Plus, eCommerce, Front-end, Node.js, Liquid, JavaScript, Full-stack, Tailwind CSS, REST APIs

Senior Full-stack Developer

2022 - 2023
Vacuumlabs
  • Implemented PKI for secure transaction signing in a new mobile banking application, using Koin and Flutter to ensure the integrity and authenticity of sensitive banking operations, such as money transfers and device registration.
  • Used Bouncy Castle for cryptographic hashing to work on both the mobile app’s signature generation and back-end verification.
  • Maintained and enhanced internal developer and analyst tools, introducing new features and increasing test coverage, improving reliability and ease of use in daily workflows.
Technologies: Kotlin, Spring Boot, React, TypeScript, PostgreSQL, Back-end Development, API Development, Back-end, Dart, Front-end, Node.js, JavaScript, Full-stack, REST APIs, Docker

Senior Full-stack Engineer | Team Leader

2021 - 2022
Gig-a Bank
  • Implemented a ledger system on the back end using Kotlin and Spring Boot.
  • Integrated the application with another bank respecting the Zengin System and an anti-money laundering (AML) provider.
  • Developed the mobile application in Flutter and used CodeMagic and Google Play Console for publishing the app to internal testers.
  • Collaborated with the Product Owner, planned the roadmap, and groomed sprints.
  • Set up the infrastructure on AWS using VPC, ALB, ECS, RDS, and Cognito.
Technologies: Kotlin, Spring Boot, Flutter, PostgreSQL, Amazon Web Services (AWS), API Integration, Relational Databases, Back-end Development, API Development, Architecture, Test-driven Development (TDD), Back-end, Dart, Front-end, Full-stack, REST APIs, Docker

Senior Full-stack Developer

2021 - 2021
Deliberate AI
  • Integrated the product with DocuSign and various AWS services such as S3, Transcribe, and SNS.
  • Built and maintained the user interface (UI) with React according to Figma designs.
  • Orchestrated different Python scripts and AWS services using Lambda, SNS, and SQS.
Technologies: Kotlin, Spring Boot, React, TypeScript, PostgreSQL, Amazon Web Services (AWS), Relational Databases, Back-end Development, API Development, Test-driven Development (TDD), Back-end, Front-end, JavaScript, Full-stack, REST APIs, Docker

Full-stack Developer

2020 - 2021
Clean Kitchen
  • Improved the UI/UX based on usability testing sessions and migrated the React application from JavaScript to TypeScript.
  • Integrated the application's back end with Airtable, Shopify, and AWS S3.
  • Optimized Shopify's GraphQL integration using bulk queries, thus reducing timeouts by 50%.
Technologies: Kotlin, Spring Boot, React, TypeScript, PostgreSQL, Airtable, Shopify, Shopify API, GraphQL, API Integration, Relational Databases, Back-end Development, API Development, Test-driven Development (TDD), Amazon Web Services (AWS), Back-end, Shopify Design, Shopify Liquid, Shopify Customizations, Shopify Scripts, shopify functions, Shopify Plus, eCommerce, Front-end, Node.js, Liquid, JavaScript, Full-stack, REST APIs, Docker

Full-stack Developer

2019 - 2020
Salv
  • Implemented, configured, and integrated the custom name searching plugin that calculates the ten most similar names against the queried name.
  • Created a JMeter performance test of the entire system and made it run daily on AWS to report results on Slack.
  • Fixed bugs and maintained the front-end React application.
Technologies: Kotlin, Spring Boot, React, TypeScript, Elasticsearch, Spring Data Elasticsearch, PostgreSQL, Apache JMeter, Java, API Integration, Relational Databases, Back-end Development, API Development, Architecture, Test-driven Development (TDD), Amazon Web Services (AWS), Back-end, Front-end, Full-stack, REST APIs, NoSQL, Docker

Experience

Company Website for 3D Visualization

A TypeScript application developed using Gatsby that showcases the company's products consisting of architectural and product visualization images. It also provides visitors with an easy way to connect with the company via a contact form or via scheduling a meeting. My responsibility was designing, developing, and hosting the website.

Education

2015 - 2020

Bachelor's Degree in Computer Science

Faculty of Technical Sciences | University of Novi Sad - Novi Sad, Serbia

Skills

Libraries/APIs

React, REST APIs, API Development, Shopify API, Liquid, Shopify Storefront API, Node.js

Tools

Shopify Plus, Apache JMeter

Languages

Java, JavaScript, Kotlin, TypeScript, HTML, Shopify Liquid, Dart, SQL, GraphQL, CSS

Frameworks

Spring Boot, Flutter, Tailwind CSS

Paradigms

REST, Design Patterns, Test-driven Development (TDD), Microservices

Platforms

Shopify, Amazon Web Services (AWS), Docker, Klaviyo, AWS IoT

Storage

PostgreSQL, Relational Databases, Elasticsearch, Spring Data Elasticsearch, NoSQL

Other

Software Development, Back-end Development, shopify functions, Front-end, Full-stack, Minimum Viable Product (MVP), API Integration, Architecture, Back-end, Shopify Customizations, Shopify Scripts, eCommerce, SOAP, Airtable, Gatsby, Shopify Design

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