Barcelona, Spain

Yusuf Yilmaz.

Senior Frontend / Full-Stack Software Engineer

Software engineer with 13+ years of experience, specializing in React, Next.js, TypeScript and frontend platform architecture, with full-stack delivery across Node.js, APIs and cloud infrastructure. I modernize complex applications, build reusable engineering platforms and deliver business-critical products in fintech, SaaS, gaming and telecommunications.

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Working since 20126 roles, one evolving craft

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About me

A Brief Introduction to My Background and Interests

I am a frontend-focused full-stack engineer based in Barcelona. Since 2012, I have worked across fintech, SaaS, gaming and telecommunications, combining React, Next.js and TypeScript with APIs, data and cloud infrastructure.

At dLocal, I work on Finance Core Frontend, Treasury Movements and commercial finance tools. My work includes reusable platform components, bank-account and entity management, spreadsheet-driven workflows, a Bank Movements Classifier with business rules and AI-assisted suggestions, and notification integrations.

Previously at Toptal, I built Google Ads automation tools and an AI-assisted Assets Generator, modernized approximately ten legacy web tools, and developed Slack messaging and SEM data-processing services. Earlier roles included mobile-test automation at Scopely, publisher tools at Marfeel, and customer-service platforms supporting more than 600,000 daily interactions at Turkcell.

I also build personal projects, including this portfolio and Yusuf Fitness OS: a mobile-first app for workouts, meals, daily tasks, calendar scheduling and reminders. My focus is maintainable software, clear interfaces and end-to-end product delivery.

View my Resume

Professional Experience

A Summary of My Roles, Companies, and Projects

Dec 2024 - Present
dLocal
Software Engineer III (Frontend-focused Full Stack)
Led frontend delivery across Finance Core Frontend, Treasury Movements and commercial finance tools, translating Finance and Operations requirements into maintainable workflows.
Led frontend delivery across Finance Core Frontend, Treasury Movements and commercial finance tools, translating Finance and Operations requirements into maintainable workflows.
Modernized the shared FCF monorepo with Turborepo, pnpm, TypeScript strict mode, MUI and tsdown. Standardized build configuration, reusable components, shared hooks and utilities.
Built Treasury Movements experiences for bank-account master data, entity management, Brazil trading and cross-border flows, including spreadsheet-driven templates and counterparty workflows.
Designed and delivered the Bank Movements Classifier with configurable business rules, AI-assisted suggestions, reprocessing, execution monitoring, transaction details and auditable classification decisions.
Developed threaded Slack notification flows and foundations for the FCF Notifications API. Improved quality through Storybook, Chromatic, CI checks and OpenAPI, Swagger and Postman documentation.
Built and improved CPQ payment tiers, fee configuration, pricing proposals, quote-sharing and Tradebook workflows.
Oct 2021 - Oct 2024
Toptal
Senior Full-Stack Engineer
Created an AI-assisted Assets Generator using Next.js, Dify and background processing to turn interviews into editable customer success stories with review, refinement and publishing workflows.
Created an AI-assisted Assets Generator using Next.js, Dify and background processing to turn interviews into editable customer success stories with review, refinement and publishing workflows.
Engineered eight Google Ads automation tools for keyword generation, asset reviews and dynamic content management, from solution design through testing and deployment.
Migrated approximately ten legacy web tools to Next.js. Built a centralized Slack messaging service and an ETL composer for Google Ads and BigQuery monitoring and alerts.
React
TypeScript
Next.js
SCSS
Redis
Node.js
Selected projects
CSS3 Maker
A public tool designed to simplify the creation of CSS3 styles, providing a range of customizations and previews for web developers. With CSS3 Maker, users can generate CSS code for various effects, such as gradients, transforms, transitions, and animations, helping streamline development workflows and enhance styling options with minimal effort.
CSS Minifier
A public tool for minifying CSS code, helping developers compress and optimize stylesheets. I worked on the frontend using React and Next.js to ensure smooth functionality and user-friendly interaction.
Hastebin
A public tool for sharing code snippets. I contributed to the full-stack development, focusing on building a responsive frontend with React and Next.js and ensuring proper backend integration for storing and retrieving code snippets.
HTML Minifier
A public tool for minifying HTML code, used to compress HTML files for improved performance. I was responsible for building the frontend using React and Next.js.
HTMLShell
A public tool that generates HTML code snippets. I developed the frontend using React and Next.js, ensuring a user-friendly experience for developers needing to generate HTML quickly.
JavaScript Minifier
A public tool for minifying JavaScript code, used by developers to compress and optimize their scripts. I developed the frontend interface using React and Next.js, ensuring a simple and intuitive user experience.
Keycode Tool
A public tool for developers to test and find keycodes for keyboard events. I built the frontend using React and Next.js, providing an easy-to-use interface for testing keycodes.
Oct 2020 - Sep 2021
Scopely
Senior Software Engineer
Developed frontend and backend functionality for a platform enabling game engineers to launch mobile-device tests on AWS Device Farm and inspect results and reports.
Developed frontend and backend functionality for a platform enabling game engineers to launch mobile-device tests on AWS Device Farm and inspect results and reports.
Supported a transition to micro-frontend architecture and Unity-related tooling.
Oct 2019 - Sep 2020
Marfeel
Senior Full-Stack Developer
Modernized publisher-facing web products with React and server-side rendering.
Modernized publisher-facing web products with React and server-side rendering.
Built CLI tools and generated component playgrounds to streamline integration and testing for media-provider teams.
Apr 2015 - Oct 2019
Turkcell Global Bilgi
Senior Software Engineer
Built and led development of WebChat, Chat Gateway and integration services supporting more than 600,000 daily interactions. Designed a multichannel gateway integrating 20+ client systems.
Built and led development of WebChat, Chat Gateway and integration services supporting more than 600,000 daily interactions. Designed a multichannel gateway integrating 20+ client systems.
Implemented chat configuration, transaction management and integration services with infrastructure teams.
Migrated WebChat to React and Redux in a compressed delivery window. Worked across JavaScript, Node.js, C#/.NET and real-time systems while mentoring junior engineers.
Nov 2012 - Apr 2015
SESTEK
Software Engineer
Worked on speech-engine integrations, backend APIs and cross-platform application delivery.
Worked on speech-engine integrations, backend APIs and cross-platform application delivery.
Developed text-to-speech and speech-recognition components, C++/C# web services and mobile clients using Swift and Objective-C.

Projects & Contributions

A showcase of my projects, tools and client work.

Yusuf Fitness OS
Creator
A mobile-first planning app for workouts, meals and daily tasks, with calendar scheduling, task completion, exercise details and reminders. Includes automated testing and deployment workflows.
DevHub Showcase
Creator
A developer portfolio featuring project case studies, a downloadable CV and interactive AI chat. Built with a modular Next.js and TypeScript monorepo.
CSS3 Maker
Senior Full-Stack Engineer
A public tool designed to simplify the creation of CSS3 styles, providing a range of customizations and previews for web developers. With CSS3 Maker, users can generate CSS code for various effects, such as gradients, transforms, transitions, and animations, helping streamline development workflows and enhance styling options with minimal effort.
A public tool designed to simplify the creation of CSS3 styles, providing a range of customizations and previews for web developers. With CSS3 Maker, users can generate CSS code for various effects, such as gradients, transforms, transitions, and animations, helping streamline development workflows and enhance styling options with minimal effort.
React
TypeScript
Next.js
SCSS
Visit project
Project and all rights reserved by Toptal
CSS Minifier
Senior Full-Stack Engineer
A public tool for minifying CSS code, helping developers compress and optimize stylesheets. I worked on the frontend using React and Next.js to ensure smooth functionality and user-friendly interaction.
Hastebin
Senior Full-Stack Engineer
A public tool for sharing code snippets. I contributed to the full-stack development, focusing on building a responsive frontend with React and Next.js and ensuring proper backend integration for storing and retrieving code snippets.
HTML Minifier
Senior Full-Stack Engineer
A public tool for minifying HTML code, used to compress HTML files for improved performance. I was responsible for building the frontend using React and Next.js.
HTMLShell
Senior Full-Stack Engineer
A public tool that generates HTML code snippets. I developed the frontend using React and Next.js, ensuring a user-friendly experience for developers needing to generate HTML quickly.
JavaScript Minifier
Senior Full-Stack Engineer
A public tool for minifying JavaScript code, used by developers to compress and optimize their scripts. I developed the frontend interface using React and Next.js, ensuring a simple and intuitive user experience.
Keycode Tool
Senior Full-Stack Engineer
A public tool for developers to test and find keycodes for keyboard events. I built the frontend using React and Next.js, providing an easy-to-use interface for testing keycodes.

Skills

My skills and areas of expertise

Frontend
React
Next.js (App Router)
TypeScript
JavaScript
Redux
Zustand
MUI
Tailwind CSS
SSR
Micro-frontends
Design systems
Backend & data
Node.js
REST APIs
.NET/C#
Prisma
PostgreSQL
MSSQL
MongoDB
Redis
Kafka.js
BigQuery
ETL
Ai & integrations
Dify
AI-assisted workflows
Slack APIs
Google Ads APIs
Automated notifications
Platform & quality
Monorepos
Turborepo
Docker
Kubernetes
AWS
Google Cloud
GitHub Actions
CI/CD
Storybook
Chromatic
Jest
React Testing Library
Playwright
Cypress

Education & Credentials

Academic Background and Achievements

Jan 2013 - Jan 2016
Boğaziçi University
M.Sc. in Software Engineering
Jan 2007 - Jan 2012
Istanbul Technical University
B.Sc. in Control and Computer Engineering

Languages

Turkish (Native) · English (Fluent) · Spanish (Intermediate)

Testimonials & Referrals

Feedback from colleagues and clients

“I had the pleasure of working with Yusuf at Toptal, where he made a significant impact as a Senior Full-Stack Engineer. He is an incredibly fast developer, consistently delivering results with impressive speed and precision. Yusuf was always proactive in creating solutions, and bringing ideas to the table. His execution was top-notch, ensuring that his innovative concepts were implemented effectively.
“Yusuf would be a fantastic asset to any team, combining speed, proactivity, and a collaborative spirit to deliver exceptional results.
Marcelo Carneiro
Toptal, Team manager

Yusuf Yilmaz.

Senior Frontend / Full-Stack Software Engineer

About me

Professional Experience

dLocal

Software Engineer III (Frontend-focused Full Stack)

Toptal

Senior Full-Stack Engineer

Scopely

Senior Software Engineer

Marfeel

Senior Full-Stack Developer

Turkcell Global Bilgi

Senior Software Engineer

SESTEK

Software Engineer

Projects & Contributions

Yusuf Fitness OS

DevHub Showcase

CSS3 Maker

CSS Minifier

Hastebin

HTML Minifier

HTMLShell

JavaScript Minifier

Keycode Tool

Skills

Frontend

Backend & data

Ai & integrations

Platform & quality

Education & Credentials

Boğaziçi University

Istanbul Technical University

Languages

Testimonials & Referrals

Marcelo Carneiro