FinTech Client #3 | Senior Full Stack Developer

SD Solutions; Warszawa; On-site; PLN 180,000 - 240,000; Full time

Job summary

SD Solutions is seeking a Senior Full Stack Developer to own the frontend/mobile development for a fintech platform used by NDA and FinTech associates. You will build features for a gamified mobile app, shaping a unique user experience that blends business logic with interactive gaming, social networking, and professional training.

Requirements include 5+ years in frontend/mobile, strong React experience, and English fluency for daily collaboration with the Israel team.

Qualifications

• 5+ years frontend/mobile development experience.
• Strong production experience with React.
• Experience with React Native is a big plus.
• Proficiency in JavaScript/TypeScript and CSS.
• Experience publishing apps to Google Play and the App Store.
• Fluent in English for daily collaboration.

Responsibilities

• Develop and maintain the customer-facing native application.
• Take end-to-end ownership of Sunbeast features from concept to deployment.
• Collaborate with backend engineers to integrate APIs for a seamless UX.
• Write clean, efficient code following best practices and team standards.
• Mentor colleagues and contribute to a collaborative environment.

Skills

React

React Native

JavaScript

TypeScript

CSS

English

Education

B.Sc. in Computer Science

Tools

Playwright

WebSockets

Cursor

Claude Code

Job description

On behalf of FinTech Client #3, SD Solutions is looking for a talented Senior Full Stack Developer.

As a Frontend Engineer, you will take ownership of a strategic, gamified platform that serves as the primary engagement and social hub for tens of thousands of NDA, FinTech associates. You will develop new features for our mobile app, shaping a unique user experience that blends high-stakes business logic with interactive gaming, social networking, and professional training. In this role, you will build the next generation of communication and reward tools that connect our massive user base at the point of sale, directly impacting NDA, FinTech growth, and market exposure.

SD Solutions is a staffing company operating globally.

Responsibilities:

• Develop and maintain the customer-facing native application.
• Take ownership of the end-to-end development of new Sunbeast features, from concept to deployment.
• Collaborate closely with backend engineers to integrate APIs and deliver a seamless, high-performance user experience.
• Write clean, efficient, and maintainable code, adhering to best practices and team standards.
• Contribute to a collaborative environment, sharing your expertise and mentoring other team members.

Requirements:

• 5+ years of frontend/mobile development experience.
• Strong production experience with React
• 2-3 years of backend development (Java or Kotlin) is an advantage.
• Strong production experience with React Native (a big advantage —including app lifecycle and deployment to stores).
• Deep knowledge of JavaScript, TypeScript, and CSS.
• Experience publishing/maintaining apps in Google Play and the App Store.
• End-to-end ownership mindset—proactive, resourceful, self-motivated
• Resourceful, self-motivated, and capable of working independently in a fast-paced environment.
• B.Sc. in Computer Science or equivalent.
• Fluent in English (daily collaboration with the Israel team).

Preferred Experience:

• Experience with React.
• Experience with end-to-end testing frameworks like Playwright.
• Knowledge of WebSockets.
• Prior experience in a fintech company, especially with payment processing or financial services.
• Experience with AI development tools like Cursor and Claude Code

About the company:

A fintech company that builds point-of-sale financing and consumer credit products for everyday service businesses. Their solution is deployed at thousands of service locations — including auto service centers, dental offices, optical clinics, and veterinary practices — and is managed through a no-fee mobile credit card.

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