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Efim Goncharuk
Verified Expert in Engineering
Software Developer
Prague, Czech Republic
Toptal member since February 13, 2021
Bio
Efim is a UI lead software engineer with eight years of experience building multi-platform video streaming services, including video browsing, streaming, subscriptions, and payments. He has expertise in building web-based apps on the Next.js framework and six years of experience leading engineering teams. Efim is also well versed in security and communication protocols.
Portfolio
DAZN
JavaScript, TypeScript, React, CSS, Jira, Over-the-top Content (OTT)...
Morgan and Morgan Arizona PLLC
HTML, CSS, React, TypeScript, CSS-in-JS, Jest, ESLint, Zustand, Localization...
Deltatre
JavaScript, TypeScript, HaXe, React, Sass, CSS, Git, Bamboo, HTML, Front-end...
Experience
- HTML - 7 years
- JavaScript - 7 years
- HaXe - 7 years
- CSS - 7 years
- Git - 7 years
- React - 7 years
- TypeScript - 4 years
- Next.js - 3 years
Preferred Environment
WebStorm, IntelliJ IDEA, Charles Proxy, Cryptography
The most amazing...
...thing I've developed is DAZN, a subscription-based video streaming service, which could be seen as Netflix for sports.
Work Experience
Senior Front-end Developer
2022 - 2023
DAZN
- Created subscription tiering and account-sharing features for the DAZN app for multiple TV platforms.
- Integrated pay-per-view subscription for Amazon Fire TV DAZN app.
- Implemented PIN protection feature for DAZN app for multiple TV platforms.
Technologies: JavaScript, TypeScript, React, CSS, Jira, Over-the-top Content (OTT), Single-page Applications (SPAs), Figma, REST, REST APIs, HTML5, Tizen, Visio, Web Development, Video APIs, HTTP Live Streaming (HLS), Streaming, Video Streaming, Unit Testing, Web Applications, Google TV, Fire TV, Video Players, Video Livestreaming
Front-end React and TypeScript Developer and Team Lead
2021 - 2022
Morgan and Morgan Arizona PLLC
- Developed an app (Start.injury.com) that registers injury incidents with America's largest injury firm (TypeScript, React, Next.js, Emotion).
- Developed an app (Injury.com) that manages and monitors client-registered injury claims.
- Implemented complex advertisement screen animation (CSS and Emotion).
- Implemented bespoke input elements UI library like text, password, date, editable drop-down, etc., which work smoothly on desktop and mobile devices and leverage native device capabilities.
- Implemented end-to-end tests using Playwright and unit tests using Jest.
- Implemented bespoke input validation solution inspired by Yup and Formik, which is small, simple, extendable, and with no external dependencies.
- Implemented integrations with Google Tag Manager and Sentry.
- Implemented A/B testing with Google Optimize on animated advertisement screens.
Technologies: HTML, CSS, React, TypeScript, CSS-in-JS, Jest, ESLint, Zustand, Localization, Sentry, Google Tag Manager, Emotion Library, Formik, Firebase, Playwright, Yup, Next.js, REST APIs, Chakra UI, WebStorm, MacOS, Slack, HTML DOM, APIs, Google Optimize, Single-page Applications (SPAs), Figma, CI/CD Pipelines, HTML5, Startups, Web Development, Unit Testing, Web Applications, Node.js
UI Engineering Lead
2019 - 2021
Deltatre
- Developed a subscription-based video streaming service, Telecine Play. The service offers a selection of its films, including the most recent titles. New titles are added to Telecine Play as soon as the day after their Telecine premiere.
- Implemented the video playback UI and functionality.
- Optimized the application deployment through AWS CloudFront content delivery network.
- Performed code reviews in the Git source management environment.
- Created tech tasks and tracked and fixed bugs using Jira as a task and bug tracker.
- Configured continuous integration and continuous delivery (CI/CD) automation pipeline.
Technologies: JavaScript, TypeScript, HaXe, React, Sass, CSS, Git, Bamboo, HTML, Front-end, IntelliJ IDEA, Localization, REST APIs, WebStorm, MacOS, Slack, HTML DOM, APIs, Google Tag Manager, Sentry, Single-page Applications (SPAs), Google Analytics, Figma, CI/CD Pipelines, HTML5, Over-the-top Content (OTT), Tizen, Visio, Web Development, Video APIs, HTTP Live Streaming (HLS), Streaming, Video Streaming, Unit Testing, Web Applications, Google TV, Fire TV, Video Players, Video Livestreaming
UI Engineering Lead
2015 - 2019
Massive Interactive
- Developed a subscription-based video streaming service, DAZN. DAZN was launched in over 200 countries and territories worldwide.
- Implemented core reach UI elements such as rails, tiles, forms, and pages, as well as UI performance optimizations, video playback UI, and functionality.
- Integrated the app with many third-party payment systems, including payment options like credit cards, direct debit, Google payment, Amazon payment, and mobile operator payments. I also integrated the app with a fraud management system.
- Implemented multiple partnership programs, gift codes, promotions, and voucher functionality. Integrated the app with analytics platforms like Google Analytics through Google Tag Manager and Conviva.
- Performed implementation for web, Android, TVs, TV consoles, and bespoke platforms like X1 and SEMP TCL.
- Conducted code reviews in the Git source management environment.
- Led an engineering team of six people. Led Agile ceremonies, including stand-ups and grooming sessions.
Technologies: JavaScript, TypeScript, HaXe, React, RobotLegs, Redux, Sass, CSS, Git, Bamboo, Jira, Ant Design, Cordova, HTML, Front-end, Slack, IntelliJ IDEA, Node.js, WebSockets, Localization, REST APIs, WebStorm, MacOS, HTML DOM, APIs, Google Tag Manager, Sentry, Single-page Applications (SPAs), Google Analytics, Webpack, Figma, CI/CD Pipelines, HTML5, Over-the-top Content (OTT), Tizen, Visio, Web Development, WebRTC, Video APIs, HTTP Live Streaming (HLS), Streaming, Video Streaming, Unit Testing, Web Applications, Google TV, Fire TV, Video Players, Video Livestreaming
Front-end Software Engineer
2014 - 2015
Banking Software Company
- Developed a corporate internet banking system for the Česká Spořitelna Bank.
- Designed a REST API for communication with server solutions.
- Designed notification subsystem for the corporate internet banking system.
- Tracked and fixed bugs using Jira as a reporting tool.
Technologies: JavaScript, Angular, Protractor, Git, Apiary API, HTML, Front-end, WebSockets, Socket.IO, REST APIs, WebStorm, HTML DOM, APIs, Single-page Applications (SPAs), HTML5, Web Development, Unit Testing, Web Applications
Software Engineer
2007 - 2011
Sitronics
- Developed rating and discounting services for mobile operators serving millions of subscribers.
- Developed the online charging system for mobile operators serving millions of subscribers.
- Created technical tasks and tracked and fixed bugs using TFS as a task and bug tracker.
Technologies: C#, LINQ, SQL, Entity Framework, Oracle, TFS, .NET, REST APIs, APIs, Unit Testing
Experience
DAZN App
DAZN is an over-the-top sports subscription-based video streaming service. It's a multi-platform app based on JavaScript, Cordova, and HaXe, available on most internet-connected devices, including smart TVs, smartphones, tablets, PCs, game consoles, streaming sticks, and set-top boxes.
I was a senior front-end engineer and, subsequently, the team lead. I created rich user interfaces and experiences in browsing video catalogs, watching video playback, creating subscriptions, and integrating with different payment systems.
I was a senior front-end engineer and, subsequently, the team lead. I created rich user interfaces and experiences in browsing video catalogs, watching video playback, creating subscriptions, and integrating with different payment systems.
Start.injury.com
Register injury incidents with the US largest injury legal firm. A potential client goes through different (based on the injury type) simple question flows, answering in one click mostly. Advertisement animation screens are shown in between steps if needed.
App.injury.com
A client of the US largest injury legal firm can review and manage registered injury incidents. The client signs the contract, provides required documents and detailed injury descriptions, monitors the progress, and communicates with a legal team.
Skills
Libraries/APIs
React, REST APIs, WebRTC, Emotion Library, Yup, Node.js, Apiary API, LINQ, Entity Framework, Formik, Playwright, D3.js, Three.js, Socket.IO
Tools
Git, WebStorm, Slack, Jira, Bitbucket, Sentry, Google Optimize, Bamboo, TFS, Google Analytics, Webpack, Figma, Visio, IntelliJ IDEA, Charles Proxy
Languages
JavaScript, TypeScript, HaXe, CSS, HTML, HTML5, Sass, Rust, C#, SQL
Frameworks
RobotLegs, Next.js, Redux, Ant Design, Angular, Protractor, Jest, .NET
Paradigms
HTML DOM, Unit Testing, REST
Platforms
MacOS, Oracle, Firebase, Tizen, Google TV
Other
Front-end, Single-page Applications (SPAs), APIs, WebSockets, Web Development, Video APIs, Web Applications, ESLint, Zustand, Google Tag Manager, Cryptography, CI/CD Pipelines, Over-the-top Content (OTT), Startups, Video Streaming, Cordova, CSS-in-JS, Localization, Chakra UI, HTTP Live Streaming (HLS), Streaming, Fire TV, Video Players, Video Livestreaming
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