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