
Marius Vlas
Verified Expert in Engineering
Front-end Developer
Lyon, France
Toptal member since October 15, 2020
Marius is a senior full-stack engineer (10+ years), frontend-heavy (React/Next.js, Angular), with strong Python/Node.js back-end skills and AWS delivery experience. He’s shipped 30+ products end-to-end across startups and enterprises, and often owns UI/UX, system design, CI/CD, and infrastructure—especially in fast-moving startups and highly regulated environments.
Portfolio
Experience
- JavaScript - 10 years
- Angular - 9 years
- TypeScript - 9 years
- CSS - 9 years
- React - 8 years
- Node.js - 5 years
- Next.js - 3 years
- Python - 3 years
Preferred Environment
Amazon Web Services (AWS), Git, Jira, WebStorm, Webpack, Claude Code, Cursor AI, Linear, MacOS, Vite
The most amazing...
...: I built a multi-product B2B/B2C legaltech suite across multiple practice areas, owning the front end and design and contributing to the back end and security.
Work Experience
Senior Full-stack Developer & Core Engineer
Inventex Innovations Inc.
- Owned front-end architecture and delivery across 7 B2B/B2C legaltech products at a US VC-backed startup (React/Next.js/Angular, AWS); launched 5 to production. Scaled the flagship product to thousands of users; owned CI/CD and release quality.
- Led UX and front-end execution through multiple pivots (IP, property/tenant, class action/arbitration, family law), maintaining shipping velocity and quality (including WCAG 2 compliance).
- Implemented strict client and infra-side security standards, resulting in zero major front-end vulnerabilities during third-party pentesting and directly contributing to the company’s successful SOC 2 Type I certification.
- Contributed on back-end (Python, Supabase, Node.js) and infra work: designed and implemented REST APIs, database schemas, and supported the SOC 2 Type I effort (achieved) by delivering back-end features (RBAC, audit logs) for the flagship product.
Technical Founder
Alt Parts
- Built and launched the full stack (React, Node.js/Python, AWS) plus an LLM/NLP pipeline for query understanding and vehicle-fit filtering.
- Trained and deployed a domain-specific NLP-NER service for automotive part recognition (Python, spaCy).
- Owned product strategy and roadmap end-to-end: defined milestones, specs, and success metrics, then executed delivery across design, engineering, and go-to-market iterations.
- Scaled the product to 30,000 daily users at peak and handled production operations and reliability globally.
- Implemented analytics instrumentation (GA, GTM) and built BigQuery reporting to analyze user behavior and feed roadmap and UX decisions.
- Integrated monetization via major affiliate/partner marketplaces (e.g., Amazon Associates, eBay Partner Network), including tracking and attribution.
- Represented the company externally (pitch decks, investor calls, demos); selected for a featured booth at WebSummit Lisbon 2025.
Freelance Full-stack/Product Engineer
Freelance
- Overhauled UI/UX across the product suite ahead of a successful Series A, improving consistency, usability, and demo readiness.
- Cut long-term development costs for multiple clients by overhauling their codebases and introducing scalable, reusable component libraries.
- Led UI/UX design and front-end delivery across multiple products; the primary IC for architecture, execution, and iteration, with thousands of daily users.
- Delivered long-running refactor and feature work for Travelife (international sustainability audit and certification platform): iteratively decomposed a monolithic Angular app and shipped new core modules used by hotels and auditors internationally.
Senior Front-end Engineer
Qiagen
- Built a proprietary Angular component library for Qiagen's Digital Insights suite, standardizing and accelerating front-end development across the product line.
- Implemented sequencing data visualizations in Angular/TypeScript using D3 for Qiagen’s Ingenuity Pathway Analysis product, including interactive exploration of expression matrices and variant tables.
- Built multi-step funnels and form workflows to create and configure new NGS experiments, and improved charting and interaction performance across data visualization modules.
- Played a key role in delivering one of Qiagen's Ingenuity Pathway Analysis products four weeks ahead of the staging deadline.
Project Manager
Rodeapps
- Ran delivery for multiple client projects with cross-functional teams of 8+ (front-end, back-end, QA, product, and design).
- Tightened up day-to-day processes to reduce wasted time and improve predictability.
- Mentored multiple junior developers, guiding them to build their careers as fully-fledged programmers.
Front-end Tech Lead
Rodeapps
- Led multiple front-end teams (3-8 engineers/QAs) across several Angular/React apps for client work and in-house products.
- Mentored several junior engineers and onboarded senior developers transitioning to front-end/full-stack.
- Selected work: Southwest Airlines - fuel management console for Southwest’s innovation team.
Full-stack Engineer
Rodeapps
- Built and shipped back-end and front-end features on multiple products (Python, Django, Node.js, AngularJS/Angular), integrating APIs and delivering UI-heavy dashboards.
- Gained a solid grasp of back-end and front-end architecture, design patterns, Node.js, Python, Django, PostgreSQL, Angular, React, and AngularJS.
- Established engineering foundations early: repo structure, environments, CI/CD, and release process to keep shipping fast with reliable quality.
Experience
Data-Science App for a US-based Airline Company
The app has been used by the data-science, accounting, and management teams. Its primary role was to present vast amounts of tightly coupled flight data in significant visual representations.
My responsibilities:
• Conceptualized and designed the app and its features.
• Developed the entire front end.
• Facilitated efficient and transparent communication with all actors involved (the back-end team, the DevOps team, and the data-science team).
The project ended up being a success—significantly optimizing the internal data-analysis processes of my client.
Order Management System for a Construction Waste Disposal Startup
My responsibilities:
• Created and maintained the front-end architecture at the highest standard.
• Managed, guided, and assured timely deliveries by front-end and QA teams.
• Orchestrated and facilitated communication between client, product, design, development, and QA teams.
Alt Parts - Intelligent Automotive Parts Search Engine
I built the React web app and the Node.js/Python services that aggregated marketplace data and ranked results against a user’s vehicle. On the “intelligence” side, I implemented an LLM/NLP layer for query understanding and refinement, and I personally trained and deployed a domain-specific NLP/NER service (Python, spaCy) to extract automotive part entities and fitment signals from messy real-world queries. To drive iteration with real evidence, I instrumented GA and GTM event tracking and built BigQuery reporting to analyze funnels and user behavior, feeding those insights directly into product decisions and roadmap updates.
We were selected for a booth at Web Summit Lisbon, and our pitch was showcased on the main entrance display on day one. At peak, the product reached around 30,000 daily users.
Education
Bachelor's Degree in Computer Science and Economics
Babeș Bolyai University - Cluj-Napoca, Romania
Certification in Computer Science
ACADEMY+PLUS - Cluj-Napoca, Romania
Skills
Libraries/APIs
React, D3.js, Node.js, REST APIs, RxJS, Chart.js, Firebase Web SDK, Claude API, Google Maps API, Mapbox API, Jenkins Pipeline, SpaCy
Tools
Figma, Claude, Sketch, Git, Firebase Analytics, Angular Universal, Webpack, Sentry, Claude Code, CircleCI, Amazon Elastic Container Service (ECS), WebStorm, Slack, Jira, Adobe Experience Design (XD), ChatGPT, Sequelize, Amazon CloudFront, Amazon SageMaker, AWS IAM, Google Analytics
Languages
JavaScript, CSS, HTML, TypeScript, HTML5, GraphQL, CSS3, Sass, SCSS, TypeScript 5, TypeScript 4, Python, TypeScript 3, C, C Shell, Python 3
Frameworks
Angular, Next.js, Tailwind CSS, Cypress, AngularJS, Redux, Express.js, React Native, Material UI, NativeScript, Angular Material, LlamaIndex, NestJS
Paradigms
Testing, Web Architecture, Unit Testing, UX Design, Microfrontends, Agile Workflow, Database Design, Object-oriented Programming (OOP), Functional Programming, UI Design, Management
Platforms
AWS Lambda, Amazon Web Services (AWS), Firebase, Contentful, Kubernetes, Mapbox, OS X, Unix, Docker, Azure, WordPress, MacOS, Google Cloud Platform (GCP)
Storage
Amazon S3 (AWS S3), Cloud Firestore, Firebase Realtime Database, PostgreSQL, SQLite, MongoDB
Other
Web Development, Front-end, API Integration, Headless CMS, Apollo, Zustand, Charts, Dashboards, Front-end Development, Web Content Accessibility Guidelines (WCAG), WCAG 2, Full-stack Development, User Experience (UX), Leadership, Technical Leadership, Team Leadership, Firebase Cloud Functions, Progressive Web Applications (PWAs), PWA, Full-stack, Artificial Intelligence (AI), APIs, Data Visualization, Tailwind UI, Vite, Cursor AI, Pupeteer, Offline Data Synchronization, Supabase, Security, Authorization, Agentic Coding, Systems Design, Legal, Ray Tracing, Finance, Statistics, Microeconomics, Logic Design, Knowledge Management, Team Mentoring, OAuth, Storybook, ChatGPT API, ChatGPT Prompts, Back-end, Generative Artificial Intelligence (GenAI), LangChain, Linear, Client Communication, Amazon API Gateway, Startup Funding, Google Analytics 4 (GA4), Google Tag Manager, Google BigQuery, eBay Motors, eBay Partner Network, Amazon Affiliate Program
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