Ivan Vasiunin

Ivan Vasiunin

Frontend DeveloperValencia, Spain

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Summary

  • Frontend developer with nearly 10 years of commercial experience building web applications and interfaces for international products.
  • Core expertise in HTML, CSS / SCSS, JavaScript / TypeScript, responsive layouts, reusable UI components and frontend performance.
  • I review code, mentor and onboard developers, and own UI quality and performance in my area.
  • Learning AI Engineering: I completed an AI Engineer course, and this website is my first AI project.

I’m a frontend developer with nearly 10 years of commercial experience building web applications and user interfaces for international products, from marketing websites and landing pages to large-scale product platforms. My core expertise is HTML, CSS / SCSS, JavaScript / TypeScript, responsive layouts, reusable UI components and frontend performance.

At Brave Brains I work on iGaming platforms and do more than feature development: I review code, mentor and onboard developers, investigate complex UI and performance issues, and help improve UI quality and development workflows.

I’m also learning AI Engineering: I’ve completed an AI Engineer course, and this website, with its RAG assistant Elio, is my first AI project.

Experience

  1. Brave Brains

    Senior Markup Developer | UI Engineering

    –Present

    Full-time · Valencia, Spain

    • I build and review UI for large-scale iGaming platforms and am the team's go-to person for markup, SCSS and UI architecture.
    • Own frontend performance in my area and take on the most complex UI tasks.
    • Acting team lead for several weeks; the team shipped several important releases on time.
    • Mentor developers; onboarded three developers who later became a separate team.

    iGaming platforms: large-scale consumer web products for international markets, across several projects and brands. A cross-functional team of developers, QA engineers, a product owner and a team lead.

    Role

    • Implement complex interfaces from designs: semantic HTML, advanced SCSS, responsive layouts.
    • Own frontend performance in my area: find bottlenecks, propose refactoring where I see technical debt or inefficient code.
    • Take on the hardest UI tasks and investigate complex issues down to the root cause.
    • Review code for quality, maintainability, reusability, HTML structure, SCSS, performance and alignment with the architecture.
    • Mentor developers and share UI and markup practices with the team.
    • Support release readiness during critical launches.

    Highlights

    • Acting team lead. Led the team for several weeks during the team lead’s absence; the team shipped several important releases to production on time.
    • Onboarding. Over about three months, onboarded three developers who later became a separate team.
    • HTML
    • CSS
    • SCSS
    • BEM
    • JavaScript
    • TypeScript
    • Angular
    • GitLab
    • Figma

  2. BrainRocket

    Markup Developer (Middle → Senior)

    –

    Full-time · Limassol, Cyprus

    • Built and reviewed UI for large-scale iGaming platforms across several brands.
    • Fixed a homepage performance problem caused by CSS masks and ran performance reviews of supported projects, including layout-shift fixes.
    • Mentored a trainee to Junior level.
    • Joined as a strong Middle and was promoted to Senior through an internal grade review.

    iGaming platforms: large-scale consumer web products for international markets, across several projects and brands. Team of about 10: developers, QA engineers, a product owner and a team lead.

    Role

    • Implemented interfaces from designs: semantic HTML, complex SCSS, responsive layouts.
    • Built reusable components and adapted existing ones to new requirements without duplication, keeping in mind how a change affects the rest of the shared system.
    • Reviewed code for quality, maintainability, readability, reusability, HTML structure, SCSS, performance and alignment with the architecture.
    • Investigated complex UI issues down to the root cause and proposed proper fixes instead of workarounds.
    • Took part in the full delivery cycle — design, implementation, QA, fixes, release.

    Highlights

    • Homepage performance. Traced a poor Lighthouse result to CSS mask in buttons repeated across the page, rewrote the components without masks and optimized other heavy gradient components. The team gained a reusable approach to gradient UI that does not hurt rendering.
    • Performance reviews. Removed unused code, introduced SCSS mixins for reusable styles, optimized images, minimized masks and filters, and fixed layout shift (CLS) during page load.
    • Mentoring. Mentored a trainee to Junior level.
    • Promotion. Joined as a strong Middle and was promoted to Senior through an internal grade review: practical tasks and technical questions from two more experienced colleagues.
    • HTML
    • CSS
    • SCSS
    • BEM
    • JavaScript
    • TypeScript
    • Angular
    • GitLab
    • Figma

  3. Liketelecom

    Frontend Developer

    –

    Full-time · Remote

    • Built NumbersValidator, a phone-number validation web app for the company's clients; company revenue grew by 5% while it was in use.
    • Wrote JavaScript scripts that automated technical support, and built and maintained landing pages.
    • Mixed role with technical support and operations for corporate telecom clients.

    A small telecom startup serving corporate clients, including brokerage companies: call routing, auto dialers and customer support.

    Role

    • Developed JavaScript scripts that automated technical support work.
    • Built and maintained one-page websites (landing pages).
    • Handled customer inquiries, set up call routing, installed and configured software, and set up auto-dialer servers.
    • Controlled financial transactions and maintained reporting documentation.

    Highlight: NumbersValidator

    I noticed that clients’ phone-number databases were often in the wrong format and that clients could not easily check whether a number was valid or which country it belonged to. I came up with a tool to solve this and built it end to end in vanilla JavaScript: a web service for validating, cleaning, correcting and converting phone numbers. Clients used it for about six months; company revenue grew by 5% during that period.

    • JavaScript
    • HTML
    • CSS

  4. University of educational medicine

    Frontend Developer

    –

    Part-time · Remote

    • Built responsive landing pages and multi-page websites for online and offline events, often delivering a complete landing page in one day.
    • Added and improved React components in an internal dashboard for teachers.

    An organization offering online and offline courses on wellbeing and self-care, nutrition, psychology and healthy eating.

    • Developed responsive landing pages and multi-page websites, mostly for new events.
    • Added and improved React components for an internal dashboard that teachers used to track lessons and schedules and leave notes.
    • Worked with designers on the technical feasibility of UI / UX designs.
    • Optimized pages for speed and fixed bugs.

    Speed of delivery was the top priority: I regularly delivered a complete landing page in one day so that new events could launch on time.

    • HTML
    • CSS
    • JavaScript
    • React
    • Figma

  5. Own websites

    Webmaster

    –

    Part-time · Ukraine

    • Ran two information websites on WordPress with a small team of copywriters; monetized them with contextual advertising and grew traffic through SEO.
    • Ran two information websites on WordPress with a team of 2–3 copywriters and, at times, a content maker.
    • Set up contextual advertising (Google AdSense) and attracted traffic through search-engine optimization.
    • Refined the interfaces and improved the layouts.
    • Bought and sold information websites, including preparing documentation for sales and handling hosting.
    • WordPress
    • SEO
    • Google AdSense

  6. Digital Web

    Web Developer

    –

    Part-time · Mariupol, Ukraine

    • Designed and developed business websites on MODX CMS, including multi-page sites and sites with a personal account area.

    Designed and developed websites for businesses: multi-page sites, business-card sites and sites with a personal account area, on MODX CMS.

    • HTML
    • CSS
    • JavaScript
    • MODX

  7. PE «Computer»

    Technical Specialist

    –

    Full-time · Mariupol, Ukraine

    • Installed, configured and maintained accounting and reporting software for enterprise customers.

    My first job after university, a non-development role: installing, configuring and maintaining accounting and reporting software for enterprise customers.

Projects

Skills

Frontend & web
  • HTML5
  • CSS3
  • SCSS / Sass
  • BEM
  • JavaScript
  • TypeScript
  • React
  • Next.js
  • Redux
  • TanStack Query
  • Tailwind CSS
  • Bootstrap
  • styled-components
  • Angular (existing components)
  • Responsive design
  • Git / GitHub / GitLab
  • Figma
AI Engineering
  • Python
  • NLP fundamentals
  • LLMs and Transformers (GPT, BERT)
  • LangChain
  • LangGraph
  • Hugging Face
  • Vector databases
  • Foundation model APIs (OpenAI, Anthropic)
AI tools
  • Claude Code
  • Claude Skills
  • Claude Code subagents
  • Claude Cowork
  • Prompt engineering
Engineering practices
  • Code review
  • Mentoring and onboarding
  • Performance tuning
  • Agile / Scrum
  • Technical documentation
  • Cross-team collaboration

Education

Certifications and courses

Languages

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