Full Stack Developer for FinTech Banking

Full-Stack Developer (Remote) Job Description & Technical Test Opulanz — Fintech platform (Latvia & Luxembourg) PART 1 — JOB DESCRIPTION Full-Stack Developer — Remote (API Integrations Focus) About Opulanz Opulanz is a digital financial services platform for businesses in Latvia, France and Luxembourg, offering payments services, banking, accounting, company formation assistance and advisory services. We are a small, fast-moving team building a product that connects to regulated financial infrastructure. The role We're looking for an experienced full-stack developer to own and grow our platform. You'll work directly with the founder, take ownership of the codebase, and build secure, reliable integrations with third-party financial APIs (payment providers, e-signature, KYC/identity verification). This is a hands-on role for someone who writes clean, documented, production-grade code. What you'll do • Maintain and extend our existing web platform (front-end + back-end). • Build and maintain integrations with third-party APIs: payments/EMI providers, DocuSign, KYC/identity, and others. • Handle authentication, webhooks, error handling and data security across integrations. • Write clean, well-documented, tested code that another developer could pick up. • Ensure the platform meets data-protection and security best practices (GDPR context). • Collaborate directly with the founder on priorities and product direction. Must-have skills • Strong full-stack experience (front-end framework + back-end + database). • Proven experience integrating REST APIs: OAuth/token auth, webhooks, retries, error handling. • Solid understanding of web security (secrets management, input validation, HTTPS, secure data handling). • Git, clean code practices, and the discipline to document your work. • Good written English and reliable communication in a remote setup. Nice to have • Experience with fintech, payments, or regulated products. • Familiarity with EMI/payment APIs (Ebury, Paypal, or similar), e-signature APIs, or KYC providers. • Experience working solo or as a lead (you'll own the codebase). Details • 100% remote • Start: 15 august 2026 Time-zone CET • Longterm contract • Half time or full time is possible How to apply Send: (1) a short intro, (2) your CV/portfolio (3) one example of an API integration you built