Senior Backend Engineer (IAM and Billing, AI)

TL;DR

Senior Backend Engineer (IAM and Billing): Building authentication, authorization, and usage-based billing infrastructure for an open-source LLM observability platform with an accent on secure multi-tenant systems and scalable event metering. Focus on designing RBAC/ABAC permission models, integrating SSO/SAML/OAuth/Stripe, and supporting both cloud and self-hosted deployments.

Location: Europe (Berlin, London, Munich, Paris, Zurich); EU timezones required; one week per month in Berlin office

Salary: €90K - €160K

Company

Open-source LLM engineering platform now part of ClickHouse, trusted by 19 Fortune 50 companies with millions of monthly SDK downloads.

What you will do

• Own authentication and identity systems including SSO/SAML, OAuth, API key management, and session handling.
• Design fine-grained authorization with RBAC/ABAC for complex organizational structures and scoped access.
• Build usage-based billing infrastructure for accurate metering of billions of trace events, payment integrations, and invoice generation.
• Create shared platform APIs and abstractions for product teams to handle permissions and billing seamlessly.
• Support self-hosted deployments with integrations for enterprise identity providers like LDAP/OIDC/SAML.
• Scale systems for enterprise needs including audit logging, compliance, and multi-tenant isolation.

Requirements

• EU timezones and one week per month in Berlin office
• Strong backend engineering experience designing secure, reliable platform systems.
• Experience with authentication/authorization: SSO/SAML, OAuth, RBAC, API key management.
• Familiarity with billing/payments: usage-based metering, Stripe integrations, entitlements.
• Comfortable with TypeScript, SQL; attention to security, edge cases, multi-tenant environments.
• Self-organized with strong opinions on API design and system boundaries; CS/quantitative degree preferred.

Nice to have

• Multi-tenant SaaS with enterprise identity requirements.
• Usage-based billing or fintech infrastructure.
• Compliance frameworks like SOC 2, GDPR for auth/data access.
• Former founder experience.

Culture & Benefits

• Small, engineering-heavy team in Berlin/SF; trust in ownership with RFCs and personal Linear management.
• Maker schedule: minimal meetings (Monday priorities, Friday demos), whiteboard support anytime.
• Code reviews as mentorship; heavy AI tool usage in workflows.
• Open-source visibility; ship under your name with changelogs and launch videos.
• Continuous learning in fast-evolving AI space; close customer access via Slack/GitHub.

Hiring process

• Full process to offer in less than 7 days.