Petar Simic, Developer in Belgrade, Serbia
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Petar Simic

Verified Expert  in Engineering

Single-page Applications (SPAs) Developer

Belgrade, Serbia

Toptal member since November 18, 2014

Bio

Petar has extensive experience in developing web applications and custom JavaScript libraries. He is a highly responsible team player and a passionate coder who is always looking for challenge and perfection. He is very good at resolving user interface problems and interaction, and prides himself on his tenacity in solution building.

Portfolio

Jollydays
Next.js, Node.js, NestJS, Elastic, Kibana, Docker, Docker Compose, Figma...
Vertrical
Node.js, SCSS, HTML, Gatsby, Next.js, Jest, Elastic, Responsive UI...
Online Freelance Agency
CSS3, HTML5, AngularJS, Angular, JavaScript, Responsive UI, User Interface (UI)...

Experience

  • Single-page Applications (SPAs) - 14 years
  • JavaScript - 14 years
  • Responsive Layout - 10 years
  • Content Management Systems (CMS) - 8 years
  • React - 5 years
  • Node.js - 5 years
  • Angular - 4 years
  • Elasticsearch - 3 years

Availability

Part-time

Preferred Environment

Visual Studio Code (VS Code), Git, Ubuntu, Figma, Docker, Docker Compose, Elastic, Kibana

The most amazing...

...thing I've created is a dynamic web application that allows users to create multiple desktops with widgets for different data types and a social function.

Work Experience

Senior Full-stack Engineer

2022 - 2024
Jollydays
  • Designed and developed a CMS that enabled the manipulation and configuration of campaigns with data related to events of different types and content in various time intervals, at specific geographic locations, or virtually.
  • Developed the client API using Node.js, which stored data in the Elastic database, and the user interface with React that simplified the creation of event campaigns.
  • Used content relevant to the created campaign on the client-side website and filters for the user-provided terms, thus enabling fast and accurate results.
  • Planned and tracked everything in Jira within daily calls and bi-weekly team planning and reviews.
Technologies: Next.js, Node.js, NestJS, Elastic, Kibana, Docker, Docker Compose, Figma, Elasticsearch, SCSS, Responsive Web Design (RWD), Single-page Applications (SPAs), TypeScript, Tailwind CSS, TypeScript 2, Web Standards, Agile Software Development, Responsive Web Apps, Content Management Systems (CMS), Quick Study, REST, Object-oriented Programming (OOP), React, Front-end

Senior Full-stack Developer

2019 - 2022
Vertrical
  • Developed many specific modules for querying and UI rendering, using Elasticsearch, Node.js, Gatsby, React, HTML, and CSS.
  • Tracked and fixed issues in Elasticsearch queries, including optimizations and boosting query response time.
  • Planned teamwork, organized tasks and bugs owners, tracked team progress and support, and debugged blockers.
Technologies: Node.js, SCSS, HTML, Gatsby, Next.js, Jest, Elastic, Responsive UI, User Interface (UI), JavaScript, TypeScript, Elasticsearch, Figma, Responsive Web Design (RWD), Single-page Applications (SPAs), Tailwind CSS, SQL, TypeScript 2, Web Standards, Agile Software Development, Responsive Web Apps, Content Management Systems (CMS), Responsive Layout, Quick Study, REST, Object-oriented Programming (OOP), Unit Testing, React, Front-end

JavaScript/Angular Developer

2015 - 2022
Online Freelance Agency
  • Created a reusable data manager to manipulate response objects from any API configuration easily. Also supports deep binding directly on a model structure, so in return, it provides first-level data for fast-performance reading and writing.
  • Developed a reusable parser to manage several viewable items for any platform and view type (list, grid, etc.) with a simple configuration file. It also supports auto-scrolling and auto-pulling of data from the API.
  • Worked as a core team member and maintained agency talent and client platform, providing new features and maintaining reported problems and requests.
Technologies: CSS3, HTML5, AngularJS, Angular, JavaScript, Responsive UI, User Interface (UI), TypeScript, SCSS, Responsive Web Design (RWD), Tailwind CSS, Web Standards, Responsive Web Apps, Content Management Systems (CMS), Responsive Layout, Quick Study, REST, Object-oriented Programming (OOP), Dom Manipulation, Unit Testing, React, Front-end

JavaScript Engineer

2020 - 2020
Atmospheric Data Solutions, LLC
  • Involved in developing specific features on the dashboard that drew any of the selected layers (e.g., winds, temperature., etc.) and provided animation with changes for the selected timeline (from a few minutes up to 24 hours).
  • Collected and parsed all the incoming data and sorted it into a timeline to create frames that were later rendered and animated.
  • Kept track of the renderers. As the platform was rapidly developed as a start-up, I had to give my best to fix existing memory leaks and build and deliver new features.
Technologies: jQuery, JavaScript, Bootstrap, Front-end, Web GIS, NetCDF, REST, Microservices, Chart.js, OpenLayers

Developer and Team Lead

2017 - 2019
TNation
  • Managed and organized the team and interviewed new candidates. Organized training sessions to improve coding.
  • Wrote documentation and specifications for new features.
  • Created reusable components that are and can be used across the system. Components determine what the content type is and display that content as a tooltip or modal window.
  • Created migration files for seeding data and manipulating with column names and value types, using Sequelize.
  • Refactored existing components covered with tests on both sides using Angular and Node.
  • Built new UI components from the provided designs from internal company or client mocks created.
Technologies: MySQL, Node.js, Angular, Responsive UI, User Interface (UI), JavaScript, AngularJS, TypeScript, SCSS, Next.js, Figma, Responsive Web Design (RWD), Single-page Applications (SPAs), SQL, Less, TypeScript 2, Web Standards, Agile Software Development, Responsive Web Apps, Content Management Systems (CMS), Responsive Layout, Quick Study, REST, Object-oriented Programming (OOP), Unit Testing, React, Front-end

Front-end Developer

2017 - 2017
BuildFire
  • Developed custom-requested applications within the BuildFire SDK.
  • Worked with a team of designers and developers on the best UX solution for the final product.
  • Improved SDK testing tools, such as building a switch that enables different device screen size views in the testing phase. Also worked on SDK bug fixes.
Technologies: HTML5, CSS3, JavaScript, Zeplin, Web, Preact, GraphQL, Front-end

Developer

2014 - 2015
Pure Blue Software. LLC.
  • Built more than 70% of the components from scratch to make the application as light as possible due to the vast amount of active interactions and event handlers.
  • Developed a specific grid system similar to the Google Calendar but with the same experience creating tasks and drag-n-drop positioning in strictly defined columns.
  • Built the application was cross-browser compatible, and all the measures were dynamically calculated in case of screen size changes. This also involved repositioning the content and verifying that all tasks were visible to the client.
Technologies: Responsive Web Design (RWD), Graphic Design, Adobe Photoshop, Data Modeling, Vanilla JS, jQuery, jQuery UI, Dom Manipulation, Front-end

UI/UX Developer

2014 - 2015
Pure Blue Software. LLC.
  • Developed an application that tracks and organizes employees. Organizers can add and change each employee plan by interacting on the calendar. It's similar to Google Calendar.
  • Developed a custom calendar component and custom drag-and-drop component for setting employee tasks, in order to get the best performance. The app had to handle overlapping and organization of UI when multiple tasks were on the calendar.
  • Developed different user roles and views of the calendar and employee tasks.
Technologies: Responsive Web Design (RWD), Graphic Design, Adobe Photoshop, Data Modeling, JavaScript, jQuery, Responsive UI, User Interface (UI), Web Standards, Responsive Web Apps, Content Management Systems (CMS), Quick Study, Object-oriented Programming (OOP), Front-end

Web Developer

2014 - 2015
Tailor and Made
  • Built websites with full cross-browsing compatibility from all desktop browsers on Windows, Linux, and Mac to all mobile and tablet platforms.
  • Created a few quick-loading "single page" static websites which use different types of libraries and components that are optimized to work from IE8+.
  • Developed custom CSS3 animations for websites, as part of my role.
Technologies: CSS3, HTML5, JavaScript, Responsive UI, AngularJS, Web Standards, Object-oriented Programming (OOP), Front-end

JavaScript/PHP Developer

2014 - 2015
Full Dream Solutions
  • Created data communication between Unity3D (mobile, web) and different type of APIs like Shopify.
  • Built a MySQL DB with RESTful APIs for a multiplayer game.
  • Programmed a reusable JSON parser in C# that manages particular types of data as requested on one gaming product.
Technologies: MySQL, JavaScript, AngularJS, Web Standards, Quick Study, Object-oriented Programming (OOP), Front-end

Lead Front-end Engineer and Team Lead

2011 - 2014
Whitecitysoft
  • Collaborated to create a custom JavaScript MVC framework that saves implementation time and spares developers the hassle of working with HTML structures by managing everything over a controller setup and hierarchy of controllers.
  • Created hundreds of different widgets built from ten simple templates. All of them are specially made to be implemented modularly and give the developer an opportunity to create new widgets with a minimum of testing.
  • Planned and researched UI on most projects to find the best optimal solution for all three sides, including designers, developers, and users, so building projects with a streamlined user interface will work more quickly in the future.
  • Organized team members and managed code quality control.
  • Took full responsibility for the system as a whole and performed training of new staff.
Technologies: XML, Git, CSS3, CSS, HTML5, HTML, JavaScript, Responsive UI, User Interface (UI), AngularJS, SQL, Web Standards, Agile Software Development, Responsive Web Apps, Content Management Systems (CMS), Responsive Layout, Quick Study, REST, Object-oriented Programming (OOP), Dom Manipulation, Unit Testing, Front-end

Web Developer

2010 - 2011
Freelance
  • Developed a static website with a Flash introduction page.
  • Implemented multi-language support with basic CMS using PHP scripts to provide easier editing of the website text content.
  • Conducted SEO optimization. Implemented email subscribe for guests and newsletter.
Technologies: CSS, HTML, JavaScript, Figma, Object-oriented Programming (OOP), PHP, Adobe Flash, Front-end

Volunteer Java, JavaScript, and Delphi Programmer

2009 - 2009
Red Cross
  • Created an MDI application in Java and Delphi for managing data.
  • Built a generic application that is able to build independently and manage user interfaces based on database XML schematics.
  • Supported offline (local) and online (server) data storage with auto-synchronization when the app connects to the internet.
Technologies: Microsoft SQL Server, Microsoft Access, RAD Studio, Delphi, Java, SQL, Object-oriented Programming (OOP)

Online Directory

An AngularJS-based web application for an online directory of a wide range of businesses that anyone can review and check.

This application supports profile creation, reviews, and comments on different businesses. Users gain various levels of badges based on the experiences they share and are also allowed to upload photos and bookmark favorite businesses. Sharing is supported on all major applications. The application is compatible with all platforms, including mobile devices and old browsers.

Earthquake Simulator

https://earlywarninglabs.com/
An AngularJS-based web application for creating real-time simulations in the browser, with data from seismic sensors and drawing waves and effects on the map using ArcGIS API. It uses a Graham scan (algorithm) to calculate more realistic areas affected by an earthquake.

Regex Generator

An AngularJS-based web application, a generator for manipulating words and sentences to create funny letters from a serious business one. With the simple configuration file and list of words that will be replaced, the generator's built-in code is reusable and simple to modify. Also, the admin can modify the percentage of modifications the generator can make.

Interactive Organizer

Built in pure JavaScript to get the best performance, this website application manages the daily/weekly/monthly plans of each worker and client. It calculates available hours and pause offsets for each worker based on previous and next tasks that are already scheduled. Simple drag-and-drop brings each task to the calendar view, automatically applying new offsets for start and end time in the defined working hour scope.

Virtual Boards/Item Manager

A website application built on a customized Backbone library that allows users to create boards and use each of them for creating and gathering different types of items from the cloud, with Dropbox and Google Drive, from stores like Amazon, music services like Soundcloud, and user desktops. I was involved in the UI/UX development and integration. My responsibility was to implement the core architecture.

Website Video Channel

An online TV channel that provides custom videos for one particular sport. I worked on the dynamic elements of the application responsible for the video player, the relationships between galleries and players, and communication with the back end. The main gallery has different states of rolling "currently playing" video on the 1st position in the 1st row from the 2nd row.

Custom Management Tool for Air Company

A system for an aviation company that required three completely independent content management systems and two websites for customers and employees. I worked on one of the content management systems built for planning plane routes, registering routes with airports, calculating expenses, and finding the best and cheapest travel routes. My responsibility was to organize the front-end core architecture. I also developed major functionality and coordinated team efforts.

Website with Focus on Annual Reports In-Company

Three projects related to annual reports and promotion for two large global corporations. The goal was to cover a wide range of platforms, browsers, and media sizes with a static, single page that had to be fully resizable and quick-loading. Each project has about seven pages arranged in one line on the Body element, with the active one in focus and the others locked to the side like stacked pieces of paper.

Web Application for Selling Gifts and Vouchers

An application for gift sales. The company has a wide range of clients and customers, allowing clients to gain more sales for their products worldwide without pushing customers to go to stores. Everything is done via online payments and vouchers. My work was based on the content management system for this application, building a fully customized editor that allows clients to create their promotions and publish them independently of the central system.

Cinema Advertising Company

An application for a cinema advertising company that provides premium marketing and media solutions for advertisers and comprehensive representation of the cinema's advertising partners. I implemented the website application, allowing customers to register, review/rate movies, and take part in the weekly quizzes to get free tickets for the latest movies. Users can search for movies and check theater locations near a zip code.

Nialaya

https://www.nialaya.com/
An Android application for creating custom bracelets in 3D with ordering and payment mechanisms. I implemented a Shopify API and PHP RESTful service that provides all the data related to products and prices from the Shopify store server and communicates with another server where the 3D models and other application data are stored.

Cost Plus Drugs

https://costplusdrugs.com
I was a software engineer on this project. My responsibility was the development of new features, components, and optimization. Besides React on the front end, I had to develop, maintain, and support the development of new features on the back end with Node.js and GraphQL.

Search Engine Web Application

https://searchubxxx.com/
The project aims to provide a streamlined and efficient platform for users to search and access a specific adult type of content.

This single-page application (SPA) was crafted using JavaScript, the Angular framework, and essential web technologies such as HTML and CSS. My role extended beyond mere coding—I actively participated in enhancing UI/UX elements, ensuring a seamless and intuitive user experience.

Document Imaging Application

https://infasme.com/
Our client's company's purpose is to enhance the efficiency and effectiveness of document management within Microsoft SharePoint and Office 365 environments. Their innovative software solutions enable organizations to streamline document imaging, storage, and retrieval processes while ensuring regulatory compliance. By leveraging their products, businesses can maximize productivity by seamlessly integrating and optimizing their investments in SharePoint and Office 365 technologies across all facets of operations.

In my role, I played a crucial part in developing and optimizing a custom grid generator. This tool replicates the functionality of Microsoft Excel within a web browser, allowing users to view and print data in a formatted manner consistent with the original documents. Utilizing JavaScript, Bootstrap, CSS, HTML, and jQuery, I ensured that the grid generator provided a user-friendly experience while maintaining robust functionality and adherence to design specifications.
2012 - 2016

Bachelor's Degree in Software Engineering

Metropolitan University - Belgrade, Serbia

Libraries/APIs

React, Preact, Node.js, jQuery, Shopify API, Backbone.js, Chart.js, Python API, OpenLayers, jQuery UI

Tools

Git, Figma, Webpack, Elastic, Adobe Photoshop, Docker Compose, Kibana, Adobe Flash, Zeplin, Web GIS

Languages

JavaScript, CSS3, XML, HTML, CSS, HTML5, TypeScript, GraphQL, TypeScript 2, SQL, Sass, Less, SCSS, PHP, Regex, Python

Frameworks

Angular, AngularJS, Next.js, Tailwind CSS, Jest, JavaScriptCore, NestJS, Vanilla JS, Bootstrap

Paradigms

Responsive Layout, REST, Responsive Web Design (RWD), Object-oriented Programming (OOP), Agile Software Development, Unit Testing, Microservices

Platforms

Visual Studio Code (VS Code), Docker, Google Cloud Platform (GCP), Web

Storage

Elasticsearch, MySQL

Other

Responsive UI, Responsive Web Apps, User Interface (UI), Single-page Applications (SPAs), Content Management Systems (CMS), Web Standards, Quick Study, User Experience (UX), Dom Manipulation, Gatsby, Graphic Design, Data Modeling, Software Engineering, Regular Expressions, Web UX, XD to HTML, Wireframe to Product, ECM, Front-end, NetCDF

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