• Develop and maintain web applications using React JS • Build responsive and user-friendly interfaces using Tailwind CSS or Bootstrap • Translate business requirements into scalable frontend solutions • Write and maintain end-to-end (E2E) test cases using Playwright • Perform manual and automated testing to ensure application quality • Identify, troubleshoot, and resolve issues in both development and production • Collaborate with developers, designers, and product teams

• Lead the development of web interfaces in React (SPA), ensuring performance, scalability and usability; • Translate business requirements and banking customer journeys into efficient digital experiences; • Work on modernizing legacy front-ends (e.g., MVC, WebForms, older portals) to modern architectures; • Define and evolve front-end architecture standards (componentization, design systems, micro-frontends where applicable); • Integrate with backend APIs (REST/GraphQL) following security and performance best practices; • Ensure compliance with banking security requirements and LGPD (Brazilian General Data Protection Law); • Perform troubleshooting and performance optimization of critical applications; • Collaborate with backend, architecture and UX teams to ensure end-to-end consistency; • Support technical decisions and mentor more junior engineers;

• Assist in developing web-based user interfaces using TypeScript and React • Support efforts to modernize legacy applications by helping re-implement functionality in React • Utilize software engineering tools such as source control systems, build tools, and debuggers • Participate in team activities including Agile ceremonies, sprint planning, and code reviews • Collaborate with team members to troubleshoot issues and propose solutions • Contribute to testing, debugging, and improving application performance • Learn and apply best practices in software development, design patterns, and coding standards • Perform other duties as assigned

🟢 At Dev.Pro, we work on projects that impact millions of people around the world — but we know it’s the people behind the tech who make it all happen. We truly value what makes each person unique and are building a workplace that’s inclusive, friendly, and supportive. About this opportunity We are building a high-performance advertising platform that integrates directly into publisher websites via a lightweight JavaScript and React-based widget. Our system renders dynamic local classified listings post-page load and is powered by a custom header bidding stack built on Prebid.js, fully deployed on Amazon Web Services.  We are looking for a Senior JavaScript Engineer with strong AdTech experience (or adjacent high-performance frontend systems) to help scale and optimize our bidding infrastructure and on-page rendering engine.  🧩 Key responsibilities and your contribution - Architect and optimize a custom Prebid.js-based header bidding stack   - Build and maintain high-performance JavaScript integrations running on publisher websites   - Improve latency, auction efficiency, and yield optimization across ad units   - Develop and enhance React-based widgets that render dynamic local listings   - Collaborate on bidder integrations, adapters, and demand partner connections   - Debug complex issues across browser environments, third-party scripts, and ad exchanges  🟢 Tech Stack - JavaScript (ES6+), TypeScript (preferred)   - React (rendering layer for widgets)   - Prebid.js / Header Bidding   - AWS (Lambda, CloudFront, S3, etc.)   - Real-time data flows, event-driven architectures   ✅ Is that you? - 5+ years of JavaScript engineering experience   - Strong understanding of browser performance, async loading, and script execution   - Experience with AdTech ecosystems (Prebid, GAM, DSPs, SSPs) OR strong adjacent experience (high-scale JS, real-time systems)   - Familiarity with header bidding concepts (auctions, bid requests, latency tradeoffs)   - Experience debugging third-party script conflicts and optimizing page performance   - Ability to work in a fast-moving, product-driven environment ✅ Nice to have - Direct experience with Prebid.js customization or bidder adapters   - Exposure to analytics, tracking, and attribution systems  🎾 What's working at Dev.Pro like? ✔️ 30 paid days off each year — use them for vacation, holidays, or personal time ✔️ 5 paid sick days, up to 60 days of medical leave, and 6 paid days off for family events like weddings, funerals, or having a baby ✔️ Partially covered health insurance - after probation ✔️ Wellness bonus for gym memberships, sports nutrition, and similar needs Our next steps: ✅ Submit a CV in English — ✅ Intro call with a Recruiter — ✅ Internal interview — ✅ Client interview — ✅ Offer Interested? Find out more: 📋How we work 💻 LinkedIn Page 📈 Our website 💻IG Page