Senior Fullstack Developer (React / Node.js) – Fully Remote

O projekcie: FullStack Developer Senior Fullstack Developer (React / Node.js) – Fully Remote Location: Fully remote Working hours: 10:00–18:00 (UK time), no travel required Rate: PLN 120–160 / hour Project duration: Initial 2 months, extension very likely Client: International financial institution Process: 2 interview stages Team: 2 Developers, Project Manager, Architect About the Role We are looking for an experienced Senior Fullstack Developer to join a small, cross-functional team working on the expansion of an existing CRM system. The project focuses on extending a HubSpot-based solution with new frontend, backend, and integration functionalities. You will play a key role in designing and building a new custom HubSpot application for internal users, developing license and trial management features, and integrating multiple internal and external systems. The role combines hands-on development with ownership of integrations and data flow reliability. What We Offer - Fully remote work  - Competitive hourly rate: PLN 120–160  - Sports card (Multisport or equivalent)  - Private medical healthcare  - Access to learning and training platforms  - Small, experienced team with a clear technical direction  - High likelihood of project extension after 2 months  Opis Firmy Experis to światowy lider rekrutacji specjalistów i kadry zarządzającej w kluczowych obszarach IT. Z nami znajdziesz konkurencyjne oferty zatrudnienia oraz ciekawe projekty IT skierowane zarówno do ekspertów z wieloletnim doświadczeniem, jak i osób, które dopiero zaczynają swoją przygodę w branży IT. Oferujemy rekrutacje menedżerów i wysoko wykwalifikowanych konsultantów z doświadczeniem w branży IT. Experis jest częścią ManpowerGroup i został uznany za jedną z najbardziej etycznych firm na świecie. Wymagania: - Minimum 5 years of professional experience as a Fullstack Developer  - Very strong knowledge of React and TypeScript  - Solid experience with Node.js and API development  - Hands-on experience with webhooks and system integrations  - Ability to read, understand, and extend existing backend codebases  - Practical experience using Claude Code or similar AI-assisted coding tools  - English proficiency at C1 level (daily collaboration with international clients)  - Polish proficiency at B2 level or higher (internal team communication) Codzienne zadania: - Design and develop a new custom module within an existing HubSpot application  - Build user-facing interfaces for internal HubSpot users  - Implement a management panel for customer trials and licenses  - Integrate the application with existing internal APIs  - Identify and implement missing backend functionalities  - Develop integration code in Node.js connecting LMS webhooks with the authentication system  - Automate user account creation based on LMS-triggered events  - Automate user roles and permissions assignment based on learning system data  - Ensure data consistency, reliability, and observability across systems  - Handle error management, retries, and monitoring of webhook-based flows