Sii ensures that all employment-related decisions are made solely on the basis of qualifications and competencies. We are committed to equal treatment of all individuals, regardless of any protected characteristics, and promote a diverse and inclusive work environment.Join an international team working for a client in the financial sector as a Node.js Developer. This is a senior-level backend development role focused on building and maintaining robust APIs and server-side logic. You’ll collaborate with experienced engineers and contribute to a well-documented, scalable architecture. The work is mostly remote, but you will attend monthly, two/to three-day meetings in Warsaw.Your tasks Developing and maintaining API endpoints and server-side logic within SvelteKit’s server.js files and form actions Ensuring proper error handling and validation across server-side operations Building database integration layers using PostgreSQL clients Writing SQL queries for CRUD operations and implementing data models aligned with frontend needs Creating unit tests for server-side functions and API routes Participating in code reviews and following established patterns for authentication, authorization, and data fetching Debugging issues across the full stack Contributing to the documentation of API specifications and database schemas Requirements Minimum 5 years of experience with Node.js Strong understanding of backend architecture and API design Experience with PostgreSQL and writing efficient SQL queries Familiarity with unit testing and code review practices Fluent English (spoken and written) Ability to work effectively in an international team Residing in Poland required Fluent Polish required Nice-to-have requirementsExperience with SvelteWhat we offer  Great Place to Work since 2015 - it’s thanks to feedback from our workers that we get this special title and constantly implement new ideas  Employment stability - revenue of PLN 2.1BN, no debts, since 2006 on the market  We share the profit with Workers - over PLN 76M has already been allocated for this aim since 2022  Attractive benefits package - private healthcare, benefits cafeteria platform, car discounts and more  Comfortable workplace – class A offices or remote work  Dozens of fascinating projects for prestigious brands from all over the world  PLN 1 000 000 per year for your ideas - with this amount, we support the passions and voluntary actions of our workers  Investment in your growth – meetups, webinars, training platform and technology blog – you choose  Fantastic atmosphere created by all Sii Power People  Join the Sii team – develop your skills, gain experience, and build your career!