Bartlomiej Obecny, Developer in Szczecin, Poland

Bartlomiej Obecny

Full-stack Developer

Szczecin, Poland
Toptal Member Since
April 16, 2014

Bartlomiej is a true enthusiast for unsolved problems. He is a full-stack developer with more than 15 years of professional experience. Bartlomiej enjoys working with people, is not afraid of changes, is very good at interpersonal skills, and is always open to new challenges.

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LightStep (via Toptal)
TypeScript, JavaScript, Node.js, Analytics, Full-stack, Architecture...
Infinity Lending Systems (via Toptal)
Azure, SQL, TypeScript, Angular Material, Angular, Full-stack, Architecture...
Reddit (via Toptal)
Canvas, Video Streaming, Redux, React, TypeScript, Architecture...


Szczecin, Poland



Preferred Environment

Git, IntelliJ, OS X

The most amazing...

...thing I've coded was Fly3D routing between any points on a map.

Work Experience

2019 - 2021

Senior JavaScript Developer

LightStep (via Toptal)
  • Maintained the OpenTelemetry API in JavaScript for both Node.js and browser.
  • Was one of the main contributors for developing OpenTelemetry JavaScript. Created many parts of OpenTelemetry, including tracing and metrics.
  • Released stable tracing version 1.0 and experimental for metrics.
  • Reviewed many PR from many different contributors.
  • Created all main plugins for the web and also many plugins for Node.js.
  • Created the most popular exporter, Collector Exporter for OpenTelemetry JavaScript for tracking and metrics.
Technologies: TypeScript, JavaScript, Node.js, Analytics, Full-stack, Architecture, Software Architecture
2019 - 2020

Senior JavaScript Developer

Infinity Lending Systems (via Toptal)
  • Created the front-end prototype for a new payment system using TypeScript, Angular 8, and Angular Materials.
  • Created a standalone component for taking payments that can be embedded into any website.
Technologies: Azure, SQL, TypeScript, Angular Material, Angular, Full-stack, Architecture, Software Architecture
2019 - 2019

React Expert

Reddit (via Toptal)
  • Created a video module for the admin panel for approving videos. The video module supported different filters, generating thumbnails without a back end.
Technologies: Canvas, Video Streaming, Redux, React, TypeScript, Architecture, Software Architecture
2018 - 2019

Full-stack Engineer

FastSwims (via Toptal)
  • Built a working product from scratch to organize swimming competitions in the USA.
  • Created a whole back end using Node.js and Sequelize.
  • Created a front-end SPA using React, Redux, and Saga.
  • Integrated with payment systems and Mixpanel analytics.
  • Created converters for swimming results that comply with USA Swimming Data Interchange format.
  • Created auto import of swimming results from an external web page.
Technologies: Amazon Web Services (AWS), Sass, PostgreSQL, Relational Database Services (RDS), Sagas, Redux, React, Sequelize, Node.js, Full-stack, Architecture, Software Architecture
2018 - 2018

Senior JavaScript Developer

Video Chat
  • Created a Video.js plugin for WebRTC livestreaming video integrated with Wowza Servers.
Technologies: Video.js, Wowza, JavaScript, WebRTC, Full-stack, Architecture, Software Architecture
2016 - 2018

Senior JavaScript Developer

  • Created DOWNStream for Electron, an open-source project for downloading DASH movies.
  • Created a desktop app for downloading movies based on Electron and React.
  • Worked on ongoing development of PRESTOPlay for browsers.
  • Implemented smooth streaming.
  • Created a video tracking plugin for Video.js.
  • Integrated analytics for "conviva" and "nice people at work."
  • Implemented Chromecast sender and receiver.
  • Created util for processing subtitles which were images using canvas and then to be able to change the color of subtitles.
Technologies: Encrypted Media Extensions (EME), Node.js, Electron, Video Streaming, JavaScript, Full-stack, Architecture, Software Architecture
2016 - 2016

Freelance Node.js Developer

Slash-hyphen (via Toptal)
  • Added a few new features to a Slack bot.
Technologies: JavaScript, Node.js, Emacs, Botkit, Full-stack, Architecture, Software Architecture
2016 - 2016

Freelance Senior JavaScript Application Engineer

Placester (via Toptal)
  • Created a Node.js service for importing contacts.
  • Created a new extendable modal.
  • Integrated with Localytics.
  • Created a module for partner scripts so that they can inject HTML fragments and custom scripts.
  • Fixed many bugs and improved stability in the admin panel.
Technologies: Node.js, PHP, CSS3, HTML5, Less, Marionette.js, Backbone.js, JavaScript, Full-stack, Architecture, Software Architecture
2013 - 2016

Owner and Freelance Developer

  • Developed an AngularJS app for file sharing.
  • Worked on presentations for a mobile conference.
  • Worked on video and audio streaming based on Node.js and DynamoDB.
  • Worked on a document data flow app, using Node.js and AngularJS.
  • Created a finance report and statistics web app using Node.js, AngularJS, PostgreSQL, and HighCharts.
  • Worked on a new responsive web app for ING Bank Śląski using Marionette, Backbone, and Node.js.
Technologies: Python, Thymeleaf, Java, Linux, Git, jQuery, PHP, Bootstrap, Sass, CSS, HTML5, Bower, Gulp, Grunt, AngularJS, Full-stack, Software Architecture
2014 - 2015

Freelance Senior Front-end Developer (via Toptal)
  • Created a vanilla JS library for for toggling and shuffling elements on the page.
  • Improved the build process using Gulp, Jasmine unit tests, and documentation using JSDoc.
  • Integrated with and Mixpanel.
  • Used a TypeForm to collect data about pet quizzes and then presented aggregated data on a custom SVG chart.
  • Refactored campaign pages and brand pages.
  • Optimized the generation of emails using improved SQL queries and stored procedures.
  • Built a pure CSS solution for star ratings.
  • Refactored the Ouibounce library (exit intent) to work on mobile, also adding some improvements.
  • Integrated action forms.
Technologies: JSDoc,, Jinja,, Highcharts, Bash, CircleCI, Karma, Jasmine, Mixpanel, Google Analytics, MySQL, Python, Django, Handlebars, Gulp, Backbone.js, AngularJS, Sass, Stylus, CoffeeScript, JavaScript, Full-stack, Architecture, Software Architecture
2014 - 2014

Freelance Developer

FindTheBest (via Toptal)
  • Created a prototype app using AngularJS.
  • Integrated with family search API using a third-party SDK.
Technologies: Bootstrap, AngularJS, JavaScript, Full-stack, Architecture, Software Architecture
2012 - 2013


  • Created an HTML text editor in vanilla JS.
  • Developed a web app for taking notes using PHP 5, JavaScript, and Python.
  • Prototyped an e-learning platform using Java and HTML5.
  • Prototyped using
Technologies: MySQL, PostgreSQL, Apache, Debian Linux, Git, jQuery, Python, PHP 5, JavaScript, CSS, HTML5, Full-stack, Architecture, Software Architecture
2009 - 2012

Senior Engineer

Nokia Gate 5
  • Worked on creating a route between points on a map using JavaScript.
  • Developed a traffic data visualization and public transportation routing using JavaScript and REST.
  • Developed Flying 3D, a simulator for any route, using JavaScript.
  • Developed an interface for on-map weather information, using Java, Python, and JavaScript.
  • Developed a build stats tool for Jenkins in Python.
  • Tested with Jasmine, JBehave, and Cucumber.
  • Applied continuous integration using Jenkins, Maven, and Puppet.
Technologies: Varnish, Splunk, Git, Subversion (SVN), Continuous Integration (CI), Puppet, Jasmine, JBehave, Behavior-driven Development (BDD), Test-driven Development (TDD), jQuery, Scrum, Agile, Apache Maven, Python, Java, JavaScript, CSS, HTML, Full-stack, Architecture, Software Architecture
2009 - 2009

Senior Developer

Web Solutions
  • Helped develop a search module for over 500 domains.
  • Developed a multi-threading service for domain search using C# IIS.
  • Developed an administration panel for office support.
  • Developed a payment gateway with credit cards, using REST and C#.
  • Used Mono framework.
Technologies: EPPlus, XML, SMTP, HTTP, Web Services, MySQL, C#, Visual Basic, Mono, ASP.NET, Visual Basic for Applications (VBA), Microsoft Visual Studio, Ajax, Test Cases, JavaScript, XHTML, Subversion (SVN), IIS, .NET, Full-stack, Architecture, Software Architecture
2007 - 2009

Team Leader

Where Are You Now
  • Implemented a new mailbox using data migration, C#, and JavaScript.
  • Developed geolocations—a map point and Google Maps—creating a new database for towns from all over the world.
  • Developed contact imports from an address book, optimizing an existing mechanism.
  • Implemented full search using Visual Basic and MS SQL.
  • Developed Carbon Footprint, calculating the amount of GHG (greenhouse gas) emissions caused directly and indirectly by traveling around the globe.
  • Developed Friends Book, a module for keeping in touch with friends. Implemented many changes and optimizations.
Technologies: XML, SMTP, HTTP, Web Services Description Language (WSDL), Scrum, FTP, Web Services, CSS, Visual Basic 6 (VB6), OpenVPN, MySQL, ASP.NET, Microsoft SQL Server, ASP, Subversion (SVN), Ajax, SQL, JavaScript, XHTML, SOAP, IIS, .NET, Full-stack, Architecture, Software Architecture
2006 - 2007

Web Developer

Where Are You Now
  • Worked on an integration with Virtual Earth and Google Maps, using JavaScript.
  • Developed a trip profile page and a travel guide using JavaScript and CSS,.
  • Worked on integration with third parties using web services and SOAP.
Technologies: XML, SMTP, HTTP, Web Services Description Language (WSDL), FTP, Web Services, CSS, Visual Basic 6 (VB6), OpenVPN, MySQL, ASP.NET, Microsoft SQL Server, ASP, Subversion (SVN), Ajax, SQL, JavaScript, XHTML, SOAP, IIS, .NET, Full-stack, Architecture, Software Architecture
2000 - 2007

Owner and Freelance Developer

  • Developed a web application for document flows inside the company, using PHP, JavaScript, CSS, and Ajax.
  • Built client/server applications for managing documents flows between architects, such as time sheets, costs, reminders, reports, LAN chat, and progress for each project, using Delphi and dBase.
  • Created a data warehouse for a company which sells steel pipes. Used PHP, JavaScript, CSS, and MySQL.
  • Programmed applications to generate statistics for the National Lottery. Used Delphi and dBase.
  • Developed a client/server application for managing and controlling the computers in an Internet Café. Used Delphi, TCP/IP, and UDP.
  • Built an application for managing a cemetery, using Delphi and dBase.
Technologies: dBASE, Apache, CSS, HTML, JavaScript, Ajax, MySQL, PHP, Software Architecture
2005 - 2006

Software Developer

Agryf S.A. - Animex Group
  • Created reports with a custom app, implemented with Delphi, dBase, and Firebird.
  • Made reports for various departments, using Delphi, dBase, Firebird, and Oracle 8i.
  • Administrated the company network, using Novell, DHCP, and SSH.
  • Developed a dedicated application for reading wages using Assembly, PASCAL, and dBase.
Technologies: SMTP, FTP, Assembler, Novell NetWare, XML, Pascal, Firebird, TCP/IP, Oracle, SSH, OpenVPN, DHCP, SQL, HTTP, Delphi
2005 - 2005

Software Developer

Public Hospital
  • Developed various small apps using Delphi and dBase.
  • Performed server administration in Novell, UNIX, Oracle, and Informix.
  • Developed the web page using JavaScript, CSS, HTML, MySQL, and PHP.
  • Implemented a daily work scheduler using PHP, Delphi, MySQL, and JavaScript.
Technologies: CSS, HTML, JavaScript, PHP, Linux, IBM Informix, Unix, SMTP, FTP, Novell NetWare, TCP/IP, Oracle, Ethernet, SSH, OpenVPN, DHCP, SQL, HTTP, Delphi
2001 - 2002

IT Technician, Software Developer

Aeris Computers
  • Created web pages using JavaScript, HTML, and CSS.
  • Built new workstations.
  • Helped with computer software and harder IT tasks.
  • Developed a desktop app for updating warehouse, in Delphi and MySQL.
Technologies: CSS, HTML, JavaScript, PHP, SQL, Delphi


A framework for collecting traces and metrics from applications. I am the maintainer for this open-source project for an OpenTelemetry API in JavaScript and TypeScript, both Node.js and browser. I created and designed the exporters, metrics, core, SDK, and plugins for auto instrumentation, including:
• XMLHttpRequest
• Fetch
• GraphQL
• Fastify
• Document load
• User interactions


Created the front-end prototype for a new payment system using TypeScript, Angular, and Angular Material.

Video Admin Module

Created a video module in the admin environment for moderating users' videos. Added various filters and controls to be able to manipulate the content. Added a module for generating thumbnails on the fly without a back end.

Tech stack: TypeScript, React, Redux, Canvas

I built the FastSwims website from scratch including the back front end.

WebRTC Video Chat

Created a WebRTC client to be used with Wowza Server for live streaming with very short response time. WebRTC client has been developed as a plugin that can be easily used with Video.js.

PRESTOPlay for Browsers

Worked on PRESTOPlay for Browsers, a video player for playing dash, smooth streaming, and HLS protected content through popular browsers.

DOWNStream for Electron
An open-source project for downloading DASH movies.

Technologies: JavaScript, Node.js, Electron

I worked on the admin panel for, which is a data company in the real estate industry. I have also created a new service in Node.js for importing contacts.

Responsive Web App for ING Bank Śląski

Worked on a new responsive web app for ING Bank Śląski using Marionette, Backbone, and Node.js.

Consumer Affairs
I worked on the Consumer Affairs website, which includes consumer news, recall information, and tens of thousands of pages of consumer reviews.

Family Tree Builder

I created a prototype integration with Family Search API using AngularJS.

Video Live Streaming

An app that shows live video streams on the web.

Back-end tech: Node.js, AWS, Elastic Beanstalk, Amazon SDK, EC2, Powershell, DynamoDB, FFMpeg, Wowza

Front-end tech: Angular, HTML5, Canvas, AudioContext, FFMpeg, Web sockets, Web workers

Document Data Flow

An app for document flow in a company with some reports. Used Node.js, PostgreSQL, Angular, HighCharts, and a dedicated server with Proxmox openVZ.

Finance Reports and Statistics

A web application for generating reports for finance metrics and statistics. Used AngularJS, Node.js, HighCharts, and PostgreSQL.

File Sharing

I built a front-end app for file sharing. Used Angular, Grunt, Karma, Jasmine, and Bootstrap.


I created a startup, a web app for taking notes.

Nokia Maps

I helped develop, now known as Mostly worked on routing.

Danish Domain Registrar
I worked on a web-based system for internet domain registration and management.

Angular i18nT
This is an Angular translation module, with custom filters for different languages and support for different grammar cases.

Intelligent House

My thesis in technical school: “Using Computers to Manage Domestic Appliances at Home."

I created and designed some electronic devices, which you could connect in clusters of up to 8. Six of them were similar to on/off switches, and two also had possibilities to change the power.

This electronic device cluster was plugged into computers using parallel ports, and windows-based application were able to manage those 8 devices. There were several possibilities for automatic management, including randomized signals. The main idea was to protect the user's home against burglars while he was away.

I received the "Technician of the Year" state award in Poland for this project, in 2000.

Technologies: C++, Bascom, Assembler, Dbase, Protel, Circuit Simulator


I worked on improvements for Slackbot.



Sass, TypeScript, ECMAScript (ES6), SQL, Less, HTML5, CSS, JavaScript, HTML, JavaScript 6, JavaScript 5, CSS3, PHP, Bash Script, CoffeeScript, Markdown, PHP 5, XHTML, Visual Basic for Applications (VBA), XML, Visual Basic 6 (VB6), Web Services Description Language (WSDL), Delphi, Pascal, Assembler, dBASE, Bash, Java, C#, Python, Visual Basic


Video.js, Jasmine, Bootstrap, AngularJS, Jinja, Ionic, JBehave, Express.js, Yii, Redux, Angular Material, Angular, Electron, Lightning Components, .NET, ASP.NET, ASP, Django, Hibernate, Spring, Mono, Thymeleaf, Jest


jQuery, Node.js, REST APIs, WebRTC, Redux-Saga, Shaka Player, HTML5 Web Workers, React, Backbone.Marionette, Underscore.js, Backbone.js, EPPlus, Handlebars, Highcharts,, Marionette.js, Google Cast API, Puppet.js, Amazon API, React Redux


Webpack, Git, Stylus, IntelliJ IDEA, Gulp, Slack, GitHub, Karma, Bower, Mercurial, Grunt, Sequelize, Jira, Apache, Puppet, Subversion (SVN), Splunk, Varnish, Microsoft Visual Studio, OpenVPN, Novell NetWare, IntelliJ, Google Analytics, CircleCI,, Emacs, Canvas, Botkit, Wowza, Adobe Photoshop, Apache Maven, Eclipse IDE


Responsive Web Design (RWD), Scrum, Design Patterns, Continuous Deployment, Continuous Integration (CI), Unit Testing, Agile Software Development, Object-oriented Programming (OOP), Web Architecture, Database Design, Testing, RESTful Development, Test-driven Development (TDD), Behavior-driven Development (BDD), E2E Testing, Continuous Delivery (CD), Continuous Development (CD), Agile, MEAN Stack


MacOS, iOS, Amazon EC2, AWS Elastic Beanstalk, Linux, Debian Linux, Tizen, Oracle, Unix, OS X, Mixpanel, Azure, Web, Windows, WordPress, Amazon Web Services (AWS)


PostgreSQL, MySQL, SQL Architecture, Firebird, IBM Informix, Amazon DynamoDB, Memcached, Microsoft SQL Server, NoSQL


HTML5 Video, Media Source Extensions, Encrypted Media Extensions (EME), Web App Development, Code Architecture, Architecture, RESTful Web Services, Full-stack, Web Development, Over-the-top Content (OTT), Software Architecture, Chromecast, HTTP Live Streaming (HLS), Smooth Streaming, Video Streaming, UI Testing, UI Frameworks, Team Leadership, Smart TV, Lighting, IIS, Test Cases, Ajax, Web Services, HTTP, SMTP, SOAP, FTP, DHCP, SSH, TCP/IP, Ethernet, JSDoc, Sagas, Relational Database Services (RDS), UX Architecture, Scraping, Technical Leadership, Analytics, Computer Science, Electronics


2000 - 2005

Master's Degree in Computer Science and Econometrics

University Of Szczecin - Szczecin, Poland

1995 - 2000

College Degree in Electronics

Technical School in Slupsk (College) - Slupsk, Poland