Senior Backend Engineer (IAM and Billing)

Stack

Responsibilities

• ▹Own authentication and identity: how users and API keys authenticate, supporting SSO/SAML, OAuth, API key management, and session handling
• ▹Design fine-grained authorization: the RBAC (and eventually ABAC) permission model for complex organizational structures, projects, and scoped access controls
• ▹Build usage-based billing infrastructure: metering pipeline that counts trace events accurately at scale, payment provider integrations, invoicing, plan management, and self-serve upgrade flows
• ▹Create shared platform APIs: clean, well-documented internal APIs for auth and billing that let product engineers move fast
• ▹Support self-hosted flexibility: clean integration with enterprise identity stacks (LDAP, OIDC, SAML)
• ▹Scale for enterprise adoption: audit logging, compliance requirements, multi-tenant isolation, complex pricing models

Requirements

• ▹Strong backend engineer excited about designing secure, reliable platform systems
• ▹Experience building authentication and authorization systems: SSO/SAML, OAuth, RBAC, API key management
• ▹Familiarity with billing or payments infrastructure: usage-based metering, payment provider integrations (Stripe or similar), entitlements
• ▹Careful thinking about security, edge cases, and failure modes, especially in multi-tenant environments
• ▹Strong opinions about API design, system boundaries, and shipping shared infrastructure safely
• ▹Comfortable reading and writing TypeScript and SQL
• ▹Empathy for self-hosted operators who need to integrate with their own identity stacks
• ▹CS or quantitative degree preferred

Nice to have

• ▹Experience building multi-tenant SaaS platforms with enterprise identity requirements
• ▹Background in usage-based billing systems or fintech infrastructure
• ▹Familiarity with compliance frameworks (SOC 2, GDPR) as they relate to auth and data access
• ▹Former founder

Soft skills

About the company

Langfuse is an open source LLM engineering platform (tracing, evaluation, prompt management), now part of ClickHouse, trusted by 19 of the Fortune 50 and 2,000+ customers. A small, engineering-heavy team based in Berlin and San Francisco, also hiring in EU timezones with one week per month in the Berlin office.