Senior Frontend Engineer

Dmytro Zeleniuk

Currently building

  • 10+ years of experience
  • New York, United States
  • Green Card Holder
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Portrait of Dmytro Zeleniuk

Selected work

  • Open source

    Web3 Connect

    Open-source Angular library that connects users to web3 applications and simplifies interacting with them.

    • Angular
    • TypeScript
    • Web3
    Web3 Connect interface

  • Social & dating

    SpicyDate

    Co-Founder & CTO

    Social and dating platform around exclusive offers and real-life events, built as one hybrid product across web, iOS and Android.

    • Angular
    • Flutter
    • Java
    SpicyDate interface

  • Browser extension

    Web3 Balances Viewer

    Chrome extension that shows the USD balance of any crypto address on the page — hover it and the wallet's holdings appear, priced live.

    • Vue.js
    • Vuetify
    • Web3
    Web3 Balances Viewer interface

Experience

Ten years, mostly in high-stakes systems

A decade of building scalable, performant and secure applications, most of it in fintech and enterprise.

  1. Jun 2024– Present

    New YorkUSA

    Senior Frontend Developer

    TEKsystemsContractfor M&T Bank

    Jun 2024 — Present·2 yrs 2 mo

    Leading development of a greenfield fintech platform for real-time peer-to-peer payments, built as a single Angular codebase that powers both the web and the native mobile applications through WebView integration.

    I own the front-end architecture and drive the technical decisions around performance, scalability and maintainability, working across backend, mobile and product teams inside a regulated banking environment where security and compliance requirements are strict.

    • Delivered a unified front-end platform serving both web and native mobile, removing the need for separate codebases
    • Built a WebView-to-native communication layer that keeps feature parity across platforms
    • Designed the state management and data flow for stability under high-load conditions
    • Cut UI latency through advanced Angular and RxJS rendering patterns
    • Angular
    • TypeScript
    • JavaScript
    • NgRx
    • RxJS
    • Karma
    • Jasmine
    • Azure
    • CI/CD
    • +5

  2. Jan 2023– Jan 2024

    New JerseyUSA

    Senior Frontend Developer

    Interactive ResourcesContractfor Lexmark

    Jan 2023 — Jan 2024·1 yr

    Worked on a large-scale enterprise platform for Lexmark, modernising a legacy Angular application running in a high-load environment.

    The focus was performance and architecture: reducing UI latency, stabilising data flow, and making the platform easier to maintain and extend as part of a longer modernisation effort.

    • Upgraded Angular versions across a legacy enterprise application and improved its performance
    • Introduced reactive state management patterns for data consistency at scale
    • Helped define the long-term strategy for moving off a monolithic architecture
    • Angular
    • TypeScript
    • JavaScript
    • NgRx
    • RxJS
    • Karma
    • Jasmine
    • Azure
    • Docker
    • CI/CD
    • +6

  3. Jun 2022– Nov 2022

    New YorkUSA

    Senior Consultant

    CapgeminiFull-timefor Morgan Stanley

    Jun 2022 — Nov 2022·5 mo

    Worked on an enterprise retirement platform covering 401(k), IRA and other investment accounts, building the interfaces used for financial planning and account management.

    Much of the work was modernisation: replacing legacy AngularJS modules with maintainable Angular components, and strengthening code quality through unit and integration tests.

    • Built reusable UI components following a service-oriented architecture
    • Refactored legacy modules, improving system performance and developer productivity
    • Delivered UI for complex financial workflows under compliance requirements
    • Angular
    • TypeScript
    • JavaScript
    • RxJS
    • AngularJS
    • REST APIs
    • Git
    • Bitbucket
    • +4

  4. Jun 2021– Feb 2022

    KyivUkraine

    Technical Frontend Engineer

    ApplicatureFull-time

    Jun 2021 — Feb 2022·8 mo

    Technical lead on a multi-tenant platform for onboarding and integrating blockchain projects, including Web3 smart contract integrations for token offerings (IDO/ICO) and payment gateway solutions.

    Beyond the front-end work, the role covered system architecture and setting up the engineering process — CI, linting, formatting, unit tests and code review practices — and translating stakeholder requirements into technical solutions.

    • Delivered a multi-tenant platform supporting several blockchain integrations in one system
    • Implemented Web3 smart contract integrations for token offerings and transaction flows
    • Established code standards, PR process and engineering practices across the team
    • Mentored junior developers
    • Angular
    • TypeScript
    • JavaScript
    • RxJS
    • Web3.js
    • Ethereum
    • Smart Contracts
    • Firebase
    • REST APIs
    • Git
    • +6

  5. Nov 2017– Jun 2021

    LvivUkraine

    Senior Frontend Developer

    OGDSolutions OÜFull-time

    Nov 2017 — Jun 2021·3 yrs 7 mo

    Built web and hybrid mobile products across two platforms.

    Gigway is a Stockholm-based marketplace connecting companies with freelancers across media, marketing, design and tech, covering the full workflow from matching through chat and contracts to payments. I developed the cross-platform mobile application and integrated analytics, push notifications and advertising tools.

    PHOTOBASH provides reference photos, 3D models and photogrammetry assets for concept art, game development and VFX. The work centred on browsing and search UI, and on loading and rendering very large media assets without degrading the experience.

    • Gigway: built the cross-platform iOS and Android app with Angular and Ionic
    • Gigway: implemented matching, real-time chat, contracts and payment flows
    • PHOTOBASH: scaled a content-heavy platform for browsing large media libraries
    • Contributed to Gigway's launch and its early growth phase
    • Angular
    • TypeScript
    • JavaScript
    • Ionic
    • RxJS
    • HTML5
    • CSS3
    • REST APIs
    • Firebase
    • Git
    • +6

  6. Oct 2016– Nov 2017

    LvivUkraine

    Frontend Developer

    Dengo SystemsFull-time

    Oct 2016 — Nov 2017·1 yr 1 mo

    Built responsive, user-friendly web applications, implementing UI components and interactive interfaces with AngularJS and jQuery.

    This is where the foundation was laid: modern layout techniques, cross-browser behaviour, performance work, and the code review habits that carried into everything after.

    • Delivered user-facing features that improved usability and engagement
    • Optimised applications for performance and cross-browser compatibility
    • HTML5
    • CSS3
    • JavaScript
    • jQuery
    • AngularJS
    • WordPress
    • Ionic
    • Git
    • +4

  7. Sep 2015– May 2016

    LvivUkraine

    Frontend Developer & Instructor

    Logos IT-AcademyFull-time

    Sep 2015 — May 2016·8 mo

    Where it started: teaching frontend development at an IT school, covering the fundamentals of HTML, CSS and JavaScript as well as the frameworks of the day.

    Explaining a concept until a room full of people can apply it turns out to be excellent preparation for technical leadership — the reasoning has to hold up out loud, not just in your head.

    • Taught HTML, CSS and JavaScript fundamentals alongside modern frameworks
    • Ran interactive classes, projects and code reviews
    • HTML
    • CSS3
    • JavaScript
    • jQuery
    • AJAX
    • Angular
    • Vue.js
    • WordPress
    • +4

Skills

What I work with

APIs & Integration

  • REST
  • GraphQL
  • WebSockets
  • Third-party SDK integrations

Architecture & Patterns

  • Component-based architecture
  • Reactive programming
  • State management
  • Micro-frontend architecture
  • Modular design

Blockchain & Web3

  • Smart contract integrations
  • Web3 APIs
  • Wallet integrations

Frameworks & Libraries

  • Angular
  • NgRx
  • RxJS
  • Ionic
  • Flutter

Languages

  • TypeScript
  • JavaScript
  • Dart

Performance

  • Lazy loading
  • Code splitting
  • Rendering optimisation
  • Memory management

Security & Fintech

  • Secure data handling
  • Authentication flows (OAuth2, OIDC)
  • Device data collection (fraud & risk)
  • High-load system design

Testing

  • Unit testing
  • Integration testing
  • End-to-end testing
  • Karma & Jasmine

Build & Tooling

  • Webpack
  • Vite
  • npm
  • Yarn
  • CI/CD pipelines
  • Docker
  • Azure

Version Control

  • Git
  • GitHub
  • GitLab
  • Bitbucket

Web & Mobile Integration

  • WebView integration
  • Hybrid app architecture
  • Cross-platform communication (Web ↔ Native)

About

I build front-ends that stay fast and maintainable as the product grows.

Ten years in, most of my work has been in banking and fintech — environments where security, compliance and high load are not negotiable. I specialise in front-end architecture: taking a product from concept to production and keeping it coherent as it scales.

Right now that means a greenfield real-time payments platform at M&T Bank, built as a single Angular codebase powering both the web app and the native mobile apps. Before that: enterprise modernisation at Lexmark, retirement products at Morgan Stanley, and Web3 smart contract integrations as a technical lead.

I care about the parts users feel — latency, responsiveness, whether an interface gets out of the way — and about the parts developers feel, which is usually what decides whether the first thing keeps being true a year later.

Contact

Let's talk

Open to senior frontend and front-end architecture roles. The quickest way to work out whether there is a fit is a short call — pick a slot that suits you, or write instead.

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Intro call

30 min

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