Daniel is available for hire
Hire DanielDaniel Kremniov
Verified Expert in Engineering
React Developer
Location
Vilnius, Vilnius County, Lithuania
Toptal Member Since
March 29, 2022
Daniel is a front-end engineer with over 10 years of commercial experience working for several UK and worldwide clients across the marketing, travel, insurance, and finance industries. He specializes in sophisticated single-page front-end application development using React and TypeScript with an emphasis on testable architecture. Daniel's clients describe him as a developer with an excellent eye for detail who can work well alongside other people.
Portfolio
Blockchain
React, Redux, MobX, RxJS, Next.js, REST, Testing, Test-driven Development (TDD)...
Vyne
React, TypeScript, JavaScript, Angular, RxJS, Architecture, Testing, HTML, CSS...
Moody's
React, TypeScript, JavaScript, Apollo, Cypress, Jest, GraphQL...
Experience
Availability
Part-time
Preferred Environment
Azure DevOps, Agile, MacOS, Git, WebStorm, Jira
The most amazing...
...React application I've been reengineering is the Blockchain.com crypto wallet with more than half a million daily users and over 37 million verified accounts.
Work Experience
Staff Front-end Engineer
2022 - PRESENT
Blockchain
- Maintained a web crypto wallet with more than half a million daily users and over 37 million verified accounts.
- Rebuilt the most revenue-generating features of the wallet, improving the overall front-end architecture, introducing testing best practices, and mentoring other team members.
- Hosted recurring front-end guild meetings for a team of 12 developers to promote high code standards and identify/resolve common impediments.
- Collaborated closely with back-end engineers to define the REST API for the project and ensure adherence to the contract between front end and back end.
Technologies: React, Redux, MobX, RxJS, Next.js, REST, Testing, Test-driven Development (TDD), HTML, CSS, Agile, Responsive UI, Jest, Cypress, TypeScript, JavaScript, A/B Testing, Unit Testing, Server-side Rendering (SSR), Tailwind CSS, Redux-Saga, Front-end, Crypto, Figma, Mentorship, Leadership, Node.js, HTML5, GitHub, Technical Architecture, Technical Leadership, Web UI, Web UX
Senior Front-end Engineer
2022 - 2023
Vyne
- Delivered a greenfield React application for automated merchant onboarding in an agile startup environment.
- Reviewed, proposed, and implemented architecture improvements for a business-critical checkout flow written in Next.js and TypeScript, used by clients including Wix, WooCommerce, Salesforce, and Big Commerce.
- Enhanced the developer workflow by introducing tools for API substitution in the local environment and automatic code generation.
- Contributed to three different codebases written in Angular.
Technologies: React, TypeScript, JavaScript, Angular, RxJS, Architecture, Testing, HTML, CSS, Agile, Startups, Jest, Next.js, Unit Testing, Server-side Rendering (SSR), Front-end, Figma, Node.js, HTML5, Technical Leadership, Web UI, Web UX
Senior Front-end Engineer
2020 - 2022
Moody's
- Developed highly interactive single-page applications with sophisticated business logic, allowing users to optimize their investment strategies using underlying Moody's products.
- Led the delivery of a highly interactive greenfield React application that assists insurers in building optimal liability-aware investment portfolios using TypeScript, React, and Apollo.
- Acted as a hands-on front-end technical lead. Managed communication with key stakeholders, resolved cross-team dependencies with two separate back-end teams, and ensured the front-end team delivered critical features with quality and timeliness.
- Created a testable front-end architecture and a clear testing strategy for the project.
- Helped the back-end team in defining a well-optimized GraphQL schema for front-end consumption.
- Actively maintained a mono-repo with reusable components used by 10 other front-end applications.
- Organized the teamwork and the application deployment on the Azure DevOps platform.
Technologies: React, TypeScript, JavaScript, Apollo, Cypress, Jest, GraphQL, Reusable Libraries, Lerna, Unit Testing, HTML, CSS, Highcharts, Webpack, Agile, Testing, Architecture, Tailwind CSS, Front-end, Figma, Mentorship, Leadership, HTML5, Technical Architecture, Technical Leadership, Web UI, Web UX
Founder and Team Lead
2018 - 2020
Right Thinking
- Built and led my own remote worldwide team of four front-end engineers.
- Managed communication with several clients and assigned work to my team.
- Delivered applications of varying complexity using the TypeScript, React, Redux, and Apollo stack.
Technologies: React, TypeScript, JavaScript, Webpack, Next.js, Server-side Rendering (SSR), Redux, User Interface (UI), User Experience (UX), Agile, Apollo, Cypress, Jest, Unit Testing, HTML, CSS, Test-driven Development (TDD), Testing, Architecture, Front-end, VWO, Material UI, Mentorship, Leadership, Node.js, HTML5, GitHub, Technical Leadership, Web UI, Web UX, Sketch
Lead Front-end Engineer
2017 - 2018
Icelolly Marketing
- Improved the performance of an existing customer-facing website by 30%, eliminating common performance bottlenecks and optimizing the critical rendering path.
- Migrated the web application from a monolithic PHP to a standalone React server-rendered architecture using a custom Node.js and Webpack setup.
- Increased overall conversion by over 20% by implementing numerous successful A/B tests in close collaboration with business stakeholders and a design team.
- Led technical vision of a team of three front-end engineers.
Technologies: JavaScript, Flow, React, Server-side Rendering (SSR), Next.js, Agile, HTML, CSS, Redux, A/B Testing, Webpack, Jest, Cypress, Unit Testing, Testing, Architecture, Redux-Saga, Front-end, VWO, Material UI, Mentorship, Leadership, Gatsby, Node.js, HTML5, Technical Architecture, Technical Leadership, Web UI, Web UX, Sketch
Web Engineer
2016 - 2017
CPP Group
- Delivered a greenfield user management project using React and Redux in an agile environment.
- Created a shared library with reusable components and style guidelines for future branded projects.
- Maintained and developed new features for an existing AngularJS application.
Technologies: React, Redux, Jest, Reusable Libraries, CSS, Angular, HTML, Agile, JavaScript, Unit Testing, Testing, Front-end, HTML5, Web UI, Web UX, Sketch
Front-end Developer
2015 - 2016
Blueclaw Media
- Delivered highly interactive and responsive websites for the sports and marketing industries using HTML, CSS, and JavaScript.
- Worked closely with back-end and design teams, as well as other business stakeholders.
- Contributed to the user experience SEO strategies.
Technologies: HTML, CSS, JavaScript, jQuery, User Experience (UX), Front-end, HTML5, Web UI
Front-end Developer
2015 - 2015
Visual & Softworks
- Delivered medium-sized projects using HTML, CSS, and Vanilla JavaScript.
- Collaborated closely with back-end developers and the creative team.
- Gained valuable experience in project management and face-to-face communication with clients.
Technologies: HTML, CSS, JavaScript, Front-end, Web UI
Experience
Blockchain.com Crypto Wallet
https://blockchain.com/Maintained front end for both custodial and non-custodial Blockchain.com web crypto wallet with more than half a million daily users and more than 37 million verified accounts.
The business recently had a huge growth and the codebases needed a significant engineering effort to keep up with the pace. I was completely rebuilding most revenue-generating features, improving overall front-end architecture. Also, I introduced testing and mentored other team members on further scaling of the application.
The business recently had a huge growth and the codebases needed a significant engineering effort to keep up with the pace. I was completely rebuilding most revenue-generating features, improving overall front-end architecture. Also, I introduced testing and mentored other team members on further scaling of the application.
Open Banking Powered Payments Platform
https://payvyne.com/I was developing front-end for open banking scale-up, simplifying merchants' payment experience by utilizing open banking technology.
I was carefully reviewing, proposing, and implementing architecture improvements for a business-critical checkout flow written in React and used by dozens of clients, including Wix, WooCommerce, Salesforce, and Big Commerce. Other highlights include the development of a greenfield React application to automate customer onboarding experience and maintenance of existing back office applications written in Angular.
I was carefully reviewing, proposing, and implementing architecture improvements for a business-critical checkout flow written in React and used by dozens of clients, including Wix, WooCommerce, Salesforce, and Big Commerce. Other highlights include the development of a greenfield React application to automate customer onboarding experience and maintenance of existing back office applications written in Angular.
Institutional Investors Analytics Platform
https://www.moodysanalytics.com/product-list/riskintegrity-investment-insightI stood up to lead a scrum team in delivering an early iteration of a front-end application that helps insurers build optimal liability-aware investment portfolios as a part of Moody's Analytics product offering.
As a hands-on front-end technical lead, I successfully managed communication with key stakeholders, resolved cross-team dependencies with multiple back-end teams, and ensured that front-end team delivered critical features in a quality and timely manner.
The work involved a deep dive into the institutional investment domain and visualization of complex asset liability models.
As a hands-on front-end technical lead, I successfully managed communication with key stakeholders, resolved cross-team dependencies with multiple back-end teams, and ensured that front-end team delivered critical features in a quality and timely manner.
The work involved a deep dive into the institutional investment domain and visualization of complex asset liability models.
Skills
Languages
TypeScript, JavaScript, HTML, CSS, HTML5, GraphQL
Frameworks
Redux, Jest, Cypress, Next.js, Angular, Tailwind CSS, Material UI
Libraries/APIs
React, jQuery, Highcharts, MobX, Redux-Saga, Node.js, RxJS
Tools
Webpack, Flow, Sketch, Figma, GitHub, Lerna, Git, WebStorm, Jira
Paradigms
Unit Testing, Testing, Test-driven Development (TDD), Agile, REST, Azure DevOps
Other
Apollo, Server-side Rendering (SSR), User Interface (UI), User Experience (UX), Responsive UI, Architecture, Front-end, Technical Architecture, Technical Leadership, Web UI, Web UX, Reusable Libraries, A/B Testing, Analytics, Mentorship, Leadership, Gatsby, Startups, Crypto
Platforms
VWO, MacOS
Education
2017 - 2020
Bachelor of Science Degree (Hons.) in Computing and IT (Software)
The Open University - Remote, United Kingdom
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