Senior Fullstack Developer

Dennis D

Information

Available hours \ week
40 h/w
Seniority level
Senior
Years of experience
7 yrs.
Location
Spain, Madrid
Nationality
Netherlands
Timezone
(GMT+01:00) Madrid

Languages

Dutch
Fluent (C2)
Spanish; Castilian
Intermediate (B1)
English
Fluent (C2)

About

Dennis is a Senior Fullstack Developer with a strong focus on building robust applications using JavaScript and TypeScript. With seven years of experience, he has specialized in frameworks like React.js and Node.js, and has successfully implemented solutions across various sectors including fintech and advertising. He possesses extensive knowledge of cloud platforms such as Google Cloud (GCP) and Docker, enhancing deployment processes and system reliability. His proficiency in PostgreSQL underpins efficient data management for the applications he develops. Dennis also leverages his ability to optimize development workflows, having re-engineered codebases for maintainability and scalability. In addition to his technical skills, he has demonstrated leadership by mentoring junior developers and authoring documentation that streamlines project knowledge. This has been crucial in fast-paced environments where team collaboration is key.

Experience

DealSize AI

Senior Front-end Engineer

About the Project

DealSize is an AI-powered platform for smart investment decisions and real-time market insights. The platform combines a chat-style assistant for technical analysis, a trade analytics module (ChartDS), and market utilities. Traders can ask natural-language questions about forex pairs, commodities, crypto, and stocks, or review their own trading performance through broker connections.

  • Fintech

Responsibilities

• Reverse engineered the codebase to map application architecture and component relationships. • Authored technical documentation to centralize project knowledge and simplify maintenance. • Optimized CI/CD pipelines to improve deployment speed and reliability.

Wheel AI

Full-stack Engineer

About the Project

Wheel AI is an AI ad agency that automates the digital marketing workflows with expert AI agents. The platform integrates with e-commerce systems, such as Shopify and WooCommerce and connects with Google and Meta Ads. It uses the Gemini API to generates campaign content and ad copy.

  • Advertising
  • Marketing
  • E-commerce

Responsibilities

• Architected scalable front-end infrastructure for improved modularity and speed. • Engineered and optimized microservices to enhance system reliability and scale. • Integrated AI capabilities via LLM APIs, utilizing prompt engineering to automate core work. • Launched high-impact platform features that increased user engagement. • Unified UI design through shared component libraries to accelerate development.

Feed

Full-stack Engineer

About the Project

Feed is a platform that automates the setup, running, and optimization of ad campaigns on Facebook and Instagram using existing organic content and default A/B testing. It repurposes existing organic content for ads and handles the heavy lifting of a media buyer by managing budgets and objectives to ensure peak campaign performance.

  • AdTech
  • Social Media

Responsibilities

• Engineered end-to-end features to expand product functionality and user capabilities. • Optimized development workflows to improve team efficiency and delivery speed. • Refactored legacy codebase to enhance readability, maintainability, and code quality. • Partnered on UI design to improve the overall user experience and interface consistency.

Social Seeder

Lead Front-end Engineer

About the Project

Social Seeder is an employee advocacy platform for SMEs and corporate organizations to recruit and activate online ambassadors on social media like Meta, LinkedIn, X and Whatsapp. It makes managing your ambassador communication intuitive and straightforward.

  • Social Media

Responsibilities

• Architected and rewrote the core codebase to modernize the stack and improve scalability. • Engineered new features from concept to deployment, expanding platform capabilities. • Mentored junior developers through code reviews and technical guidance to upskill the team. • Optimized development workflows

Skills & technologies

Circus

Front-end Engineer

About the Project

Circus is a platform for the entertainment industry that allows studios to onboard team members with a simple QR code, control complex workflows and approvals across multiple products and regions, and track time on any device to process payroll more efficiently.

  • Human Resources
  • Video Production

Responsibilities

• Engineered new application features to expand functionality and meet user requirements. • Refactored existing code to optimize performance and reduce technical debt. • Designed and executed comprehensive test cases to ensure high software quality. • Maintained the design system using Storybook to ensure UI consistency and reuse.

Skills & technologies

23G

Front-end Engineer

About the Project

23G is a digital agency leveraging cutting-edge technology to design, build, and manage applications that accelerate growth for forward-thinking companies and their clients. The work involves developing landing pages, CMS systems, intranets, and custom applications tailored to client needs.

  • Consulting Services

Responsibilities

• Developed full-stack web applications from the ground up to meet client-specific needs. • Mentored and provided technical guidance to interns to accelerate their skills and team integration. • Enhanced and optimized legacy codebases for multiple client projects to improve overall performance.

Skills & technologies

Education

Minerva Art Academy

2005 - 2010
Graphic Design