Senior Backend Engineer (Go/PHP) – CIAM Migration (Auth0)

Senior Backend Engineer (Go/PHP) – CIAM Migration (Auth0) We are looking for a Senior Backend Engineer to join a high-impact Customer Identity and Access Management (CIAM) migration project. You will play a key role in transitioning the existing identity platform from AWS Cognito to Auth0, working across both legacy PHP systems and modern Golang microservices. This is a 100% remote role (CET timezone), offered as a fixed-term contract until September 2026. Responsibilities • Implement and support the migration from AWS Cognito to Auth0 • Develop and maintain backend services in Golang and PHP • Work with both legacy monolith and modern microservices architecture • Analyze existing systems, integrations, and dependencies • Participate in technical design and migration planning • Break down complex tasks and support delivery across teams Requirements • 5+ years of experience in backend development • Strong experience with Golang (Go) and PHP • Experience working with legacy systems and monolith architecture • Solid understanding of microservices architecture • Experience with Auth0 or AWS Cognito • Good knowledge of OAuth2, OpenID Connect, JWT • Experience with REST APIs and system integrations • Strong analytical and problem-solving skills Nice to have • Experience with CIAM or identity systems • Knowledge of AWS and cloud-based architectures • Experience in system migrations or large-scale refactoring • Understanding of authentication flows and user experience