Željko is available for hire
Hire ŽeljkoŽeljko Kalezić
Verified Expert in Engineering
Software Developer
Niš, Serbia
Toptal member since January 6, 2021
Bio
Željko is a dedicated software engineer with nearly a decade of experience specializing in developing full-stack solutions using practical frameworks. Željko is not afraid of tackling large existing codebases and has no problem starting with a fresh slate.
Portfolio
CarSync
API Integration, JSON, APIs, Memcached, CSS, HTML, Google Cloud...
Amazon.com
Amazon Web Services (AWS), API Integration, JSON, APIs, REST APIs...
Global App Testing
API Integration, Ruby on Rails 5, JSON, APIs, Ruby, Redis, GraphQL, Docker...
Experience
- JavaScript - 5 years
- C#.NET - 4 years
- Ruby - 3 years
- Ruby on Rails (RoR) - 3 years
- React - 2 years
- Java - 1 year
- Kotlin - 1 year
- TypeScript - 1 year
Availability
Part-time
Preferred Environment
Terminal, JetBrains
The most amazing...
...thing I have worked on is a 100,000+ TPS pipeline orchestration platform for Amazon catalog contributions built around Kinesis.
Work Experience
Senior Software Engineer
2019 - 2021
CarSync
- Worked on a medium-sized Kotlin back end and React front end that provides car management automation and analytics for peer to peer car sharing on Turo, Getaround, and Hyrecar.
- Helped create a stable and functional free calendar sync service for Turo, Getaround, Ryde, and HyreCar hosts across the country.
- Led and mentored junior software developers in the team (direct reports).
Technologies: API Integration, JSON, APIs, Memcached, CSS, HTML, Google Cloud, Cloud Firestore, MySQL, Kotlin, React
Software Development Engineer II (L5)
2019 - 2019
Amazon.com
- Contributed to the development of a 100,000 TPS pipeline orchestration platform; more information can be found at Youtube.com/watch?v=9MZtBMjOFsQ.
- Worked on an Amazon catalog contribution platform built around Kinesis that provides sequencing, optimistic batching, and duplicate suppression while at the same time lowering costs.
- Migrated internal services from Oracle to DynamoDB.
Technologies: Amazon Web Services (AWS), API Integration, JSON, APIs, REST APIs, Amazon Kinesis, Amazon DynamoDB, Java
Software Engineer
2017 - 2018
Global App Testing
- Worked on a crowd testing solution that enables tech teams to test in over 105 countries with over 40,000 professional testers using real devices and environments.
- Helped create a blend of people and technology to build a scalable solution, working with QA teams across the world to extend their testing coverage; the whole system was hosted on AWS and orchestrated using Docker and Kubernetes.
- Worked on medium-sized Rails application admin panel and APIs and React front-end applications that communicate with the Rails back end using GraphQL.
Technologies: API Integration, Ruby on Rails 5, JSON, APIs, Ruby, Redis, GraphQL, Docker, React, PostgreSQL, Ruby on Rails (RoR)
Web Programming Lecturer
2017 - 2018
NiCAT companies
- Worked as a web programming lecturer and taught ASP .NET MVC in my local community in a program sponsored by Serbian government and local IT cluster.
- Oversaw and was responsible for all aspects of the course designing the curriculum, creating the teaching materials, lecturing, and grading.
- Led 45 people to successful course completion with more than 50% finding their first IT job after completing the course.
Technologies: JSON, APIs, JavaScript, CSS, HTML, ASP.NET
Senior Software Engineer
2017 - 2017
Atomia
- Helped with the development of a type of cloud hosting software for hosting companies and telcos all across the world.
- Worked on a large-scale .NET project which is a complete software solution for cloud and web hosting services billing, provisioning, and user control panels.
- Implemented new features and resolved bugs for several releases.
Technologies: API Integration, JSON, APIs, Windows Services, Knockout (Knockout.js), .NET
Software Engineer
2015 - 2017
Mainframe2
- Helped to implement a platform that simplifies the delivery of virtual apps and desktops on any cloud.
- Worked on a medium-sized Rails project that is a single pane of glass for the rest of the system; communicated with the rest of the system was done through APIs and RabbitMQ using Sneakers and WebSockets.
- Enabled faster time to value via a consistent end-user experience that enables organizations to move at the speed their business needs.
- Implemented a WebSockets PoC that reduced the number of requests by 80%, compared to the existing polling-based solution.
Technologies: Amazon Web Services (AWS), API Integration, Ruby on Rails 5, JSON, APIs, Ruby, Memcached, ES6 Promises, JavaScript, PostgreSQL, Heroku, RabbitMQ, Ruby on Rails (RoR)
Full-stack Engineer and Team Lead
2011 - 2015
SmartNet Technologies
- Worked on a wide range of projects, from small to large, in different areas.
- Managed and led a small development team of four people.
- Responsible for technical leadership, product definition, project implementation, and client communication.
- Helped double the company size from five to ten people.
Technologies: API Integration, JSON, APIs, CSS, HTML, IIS, SQL, ASP.NET, C#.NET
Experience
CarSync
https://carsync.io/I helped to build a free calendar sync service for Turo, Getaround, Ryde, and HyreCar hosts across the US. CarSync integrates with the car-leading sharing platforms, smart cars, OBD devices, and toll agencies.
Global App Testing
https://www.globalapptesting.com/Global App Testing is a crowd testing solution that enables tech teams to test in over 105 countries with over 40,000 professional testers using real devices and environments.
Focusing on autonomous testing augmented with humans and blending of crowd testing and intelligent automation helps clients release high-quality software around the world.
Focusing on autonomous testing augmented with humans and blending of crowd testing and intelligent automation helps clients release high-quality software around the world.
IT Bootcamp
https://itobuke.rs/I worked as a web programming lecturer teaching ASP .NET MVC in my local community in a program sponsored by Serbian government and local IT cluster. I was responsible for all aspects of the course including designing the curriculum, creating the teaching materials, lecturing, and grading.
Frame
https://fra.me/Frame runs Windows applications in the cloud. Access them from your browser—no plugins required. Frame runs your applications on powerful servers in the cloud and delivers the user interface to your browser as an optimized H.264 video stream.
Education
2005 - 2015
Master's Degree in Information Technology
University of Nis, Faculty of Electronic Engineering - Niš, Serbia
Skills
Libraries/APIs
React, Vue, REST APIs
Tools
RabbitMQ, JetBrains, Terminal
Languages
Ruby, C#.NET, JavaScript, Java, Kotlin, TypeScript, HTML, SQL, GraphQL, CSS
Frameworks
Ruby on Rails (RoR), Ruby on Rails 5, Unity3D, ASP.NET, .NET, Knockout (Knockout.js)
Platforms
Amazon Web Services (AWS), Heroku, Docker
Storage
JSON, Google Cloud, PostgreSQL, Memcached, Cloud Firestore, MySQL, Amazon DynamoDB, Redis
Other
Software Engineering, APIs, API Integration, IIS, ES6 Promises, Windows Services, Amazon Kinesis
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