Aleksandar is available for hire
Hire AleksandarAleksandar Varicak
Verified Expert in Engineering
Software Developer
Belgrade, Serbia
Toptal member since March 15, 2019
Bio
Aleksandar has more than 15 years of experience in various parts of the software development cycle. He is a delivery director at a company named Vrize. As Vrize just started an office in Serbia, Aleksandar is responsible for employees and ongoing projects. He connects daily with teams from different parts of the world and drives projects to success. He also appoints team leads and project managers as Vrize is a fast-growing company.
Portfolio
Par
Agile, Jira, PHP, Vue, Code Review, Debugging, Software Architecture...
Vrize
React, Python, Java, Amazon Web Services (AWS), Jenkins, Bitbucket, Datadog...
Factory World Wide
Gherkin, Redis, MySQL, Jenkins, jQuery, Django, SQLAlchemy, Flask-RESTful...
Experience
- Python - 13 years
- Agile - 11 years
- API Integration - 11 years
- REST APIs - 10 years
- Project Management - 10 years
- SQLAlchemy - 10 years
- Redis - 7 years
- PostgreSQL - 6 years
Availability
Part-time
Preferred Environment
Python
The most amazing...
...project I've been working on is a casino management system that is currently used in more than 15 online casinos.
Work Experience
Group Engineering Manager
2023 - PRESENT
Par
- Collaborated with multiple teams to introduce missing features to compete in the US restaurant menu market. These features will enable our part of the company to become profitable by the end of 2025.
- Helped to reorganize our part of the company to reduce costs and increase productivity.
- Introduced multiple procedures and processes to track progress, increase productivity, reduce costs, and help the company navigate to achieve goals.
Technologies: Agile, Jira, PHP, Vue, Code Review, Debugging, Software Architecture, Technical Leadership, CI/CD Pipelines
Delivery Director
2022 - 2023
Vrize
- Set up a company structure for the Serbia office, working with HR to interview new employees and expand teams.
- Drove existing projects to satisfy the client and team needs.
- Implemented work procedures to improve the quality of delivered software.
- Collaborated with team leads to create an education program for developers.
Technologies: React, Python, Java, Amazon Web Services (AWS), Jenkins, Bitbucket, Datadog, Bitrise, Git, Code Review, Debugging, Technical Leadership
CTO
2013 - 2022
Factory World Wide
- Designed and developed the most complex platform parts for land-based and web casinos/gambling.
- Created a multiservice system (gambling platform) using Python, Go, GRPC, FastAPi, Django, PostgreSQL, Redis, and RabbitMQ. Added GitLab CI and helped with Nomad/Docker orchestration set up.
- Introduced new architecture with microservices (Nameko on Python) as back end and Angular as front-end.
- Designed the system architecture for our main projects using MySQL, Python, Flask, SQLAlchemy, Redis, JavaScript, and Angular. Worked on five projects with the stack mentioned.
- Designed a mentoring system used in the company. Mentored and organized developers.
- Contributed to the quality management system (QMS) and worked on the company strategy.
- Introduced BDD (Gherkin/Cucumber) and automated tests to one of our projects. Created build jobs using Jenkins.
Technologies: Gherkin, Redis, MySQL, Jenkins, jQuery, Django, SQLAlchemy, Flask-RESTful, Nameko, Flask, Python, PostgreSQL, FastAPI, GitLab CI/CD, Project Management, Quality Assurance (QA), JavaScript, Data Analysis, Data Analytics, REST APIs, API Integration, SQL, APIs, Architecture, XML, XML Parsing, Object-relational Mapping (ORM), Back-end, Git, API Development, Back-end Development, Code Review, Debugging, Transactions, CTO, Software Architecture, Software Development, Technical Leadership, CI/CD Pipelines, Agile
CTO
2012 - 2013
Alteatec
- Served as part of the top management structure of the company. Worked on company strategy and interviewed senior developers.
- Acted as a project manager for the first customer (online casino and lotto platform).
- Worked with customers to specify requirements and providing offers.
- Assembled teams dedicated per project, providing education of senior developers and other project managers.
Technologies: Agile, ZeroMQ, Redis, MySQL, jQuery, PHP, Python, Project Management, Quality Assurance (QA), JavaScript, Data Analysis, Data Analytics, REST APIs, API Integration, SQL, APIs, Architecture, XML, XML Parsing, Object-relational Mapping (ORM), Back-end, Git, API Development, Back-end Development, Code Review, Debugging, Transactions, CTO, Software Architecture, Software Development, Technical Leadership, CI/CD Pipelines
Lead Developer
2011 - 2012
Alteatec
- Led a group of five developers, primarily juniors. Besides working on projects, I've been educating the whole team on front-end and back-end technologies.
- Designed the architecture for the system and built the first app server using Python, SQLAlchemy, MySQL, and ZeroMQ as communication layer with the web server.
- Improved reporting system to the data warehouse for better analytics. Changed existing PHP implementation to use Python instead and increased ETL speed by more than 30%. Introduced the standard for easier reports creation.
- Worked with clients to gather requirements and transform them into tasks for the team. worked with several client teams including customer support, casino manager, game manager, and risk manager.
- Integrated several payment gateways (Skrill, Neteller, WorldPay, and several less known providers from Scandinavia).
Technologies: jQuery, Redis, MySQL, SQLAlchemy, Python, PHP, Android SDK, JavaScript, API Integration, SQL, APIs, Architecture, XML, XML Parsing, Object-relational Mapping (ORM), HTML, CSS, Responsive Web Apps, Back-end, Git, API Development, Back-end Development, Code Review, Debugging, Transactions, Software Architecture, Software Development, Technical Leadership
Software Engineer
2008 - 2011
Wowd
- Designed and developed a data warehouse in MySQL using star schema.
- Created web server for populating a data warehouse. The server was receiving information from clients every 15 minutes. The amount of data collected for one day was more than 5GB. Java with NIO.
- Developed a dozen ETL scripts to compress data due to low disk space. Scripts were done using Java.
- Made the web view for reports using jQuery and Java.
- Created the first iPhone app for the system using Objective C.
- Contributed as part of the QA team. Created testing procedures and performed final testing of new releases (as I was the only person in the team having MacOS).
Technologies: Objective-C, MySQL, Java, API Integration, SQL, APIs, Architecture, XML, XML Parsing, HTML, CSS, Responsive Web Apps, Back-end Development, Debugging, Software Development
Experience
Casino Management System
This enterprise system contained several parts:
- Application system for storing user details, wallets, bonuses, tournaments, and third-party integrations.
- Web system for showing a casino website managed via the back office system. Both systems were connected to the application system with different roles.
- Redis cache used for game transactions. Thousands of transactions can happen at any second, so a standard database system cannot handle that amount of transactions without creating huge latency. We've created a Redis system as a layer between the database and third parties that were storing each transaction, and we created scripts for dumping data from Redis to the database in a batch.
- Database layer. Master-slave configured that all updates are done to the master database and all select queries from the slave.
- Reporting system. A separated system that was aggregating data from the relational database into a data-warehouse-like structure for displaying needed reports.
Most noticeable game providers: NetEnt and Microgaming.
Most noticeable payment processors: Skrill, PayPal, Worldpay, Neteller
The platform is currently used in more than 15 live casinos.
- Application system for storing user details, wallets, bonuses, tournaments, and third-party integrations.
- Web system for showing a casino website managed via the back office system. Both systems were connected to the application system with different roles.
- Redis cache used for game transactions. Thousands of transactions can happen at any second, so a standard database system cannot handle that amount of transactions without creating huge latency. We've created a Redis system as a layer between the database and third parties that were storing each transaction, and we created scripts for dumping data from Redis to the database in a batch.
- Database layer. Master-slave configured that all updates are done to the master database and all select queries from the slave.
- Reporting system. A separated system that was aggregating data from the relational database into a data-warehouse-like structure for displaying needed reports.
Most noticeable game providers: NetEnt and Microgaming.
Most noticeable payment processors: Skrill, PayPal, Worldpay, Neteller
The platform is currently used in more than 15 live casinos.
Closir | Corporate Access Platform
https://www.closir.com/Closir is a corporate access platform connecting investors with emerging market companies. The platform is being used by more than a dozen companies (paying customers) in the emerging market and the most selling feature is the corporate calendar.
The following technologies were used:
• Python with Nameko for microservices. The biggest challenge was to separate services, not to be inter-dependable.
• Python API that communicates with the microservices back end. API is done via Flask and Flask-RESTful.
• Web app (except corporate calendar) - done in Angular.
• Corporate calendar - done in AngularJS (Angular 1).
The following technologies were used:
• Python with Nameko for microservices. The biggest challenge was to separate services, not to be inter-dependable.
• Python API that communicates with the microservices back end. API is done via Flask and Flask-RESTful.
• Web app (except corporate calendar) - done in Angular.
• Corporate calendar - done in AngularJS (Angular 1).
Cool Cities
More than 75.000 users use the app. The app's main purpose is to bookmark places that other people share and you want to visit.
The app is available on both iOS and Android. The back-end is done with Python and Flask.
The app is available on both iOS and Android. The back-end is done with Python and Flask.
Education
2004 - 2008
Bachelor's Degree in Advanced Software Technologies
Faculty of Science, Union University - Belgrade, Serbia
Skills
Libraries/APIs
REST APIs, API Development, jQuery, SQLAlchemy, Flask-RESTful, ZeroMQ, React, Vue
Tools
Git, Jenkins, GitLab CI/CD, Bitbucket, Jira
Languages
Python, SQL, JavaScript, XML, HTML, Objective-C, Gherkin, Java, PHP, CSS
Paradigms
Agile, Object-relational Mapping (ORM), Microservices
Storage
PostgreSQL, Redis, MySQL, XML Parsing, Datadog
Frameworks
Flask, Django, Nameko, Android SDK
Industry Expertise
Project Management
Platforms
Amazon Web Services (AWS), Bitrise
Other
API Integration, APIs, Architecture, Back-end, Back-end Development, Code Review, Debugging, Transactions, Software Architecture, Software Development, Technical Leadership, Quality Assurance (QA), FastAPI, Data Analysis, Data Analytics, CTO, CI/CD Pipelines, Responsive Web Apps
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