Senior Backend Engineer (IAM and Billing)

Langfuse
Zurich, Munich, Paris, Berlin
Workplace: HybridFull timeEUR 90,000 - 160,000 annuallyFunction: Software EngineeringSkills: ["Security-minded","API design","System design","Self-directed","Accountability"]

Own Langfuse’s authentication, authorization, and usage-based billing—the shared platform every product team depends on. Design secure identity flows (SSO/SAML, OAuth, API keys), architect fine-grained RBAC/ABAC permissions, and build scalable metering and invoicing for trace-volume billing. Deliver clean internal platform APIs that work across Langfuse Cloud and self-hosted deployments, handling multi-tenant security, audit needs, and edge cases end to end.

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FursaFursa
Langfuse
Langfuse
3 months ago

Senior Backend Engineer (IAM and Billing)

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Source: Company careers pageValidated by: Fursa AI
Last checked: 8 hours agoStatus: Live

Job Summary

Own Langfuse’s authentication, authorization, and usage-based billing—the shared platform every product team depends on. Design secure identity flows (SSO/SAML, OAuth, API keys), architect fine-grained RBAC/ABAC permissions, and build scalable metering and invoicing for trace-volume billing. Deliver clean internal platform APIs that work across Langfuse Cloud and self-hosted deployments, handling multi-tenant security, audit needs, and edge cases end to end.
Location: Zurich, Munich, Paris, Berlin
Workplace: Hybrid
Employment Type: Full time
Job Function: Software Engineering
Seniority: Mid level

Key Responsibilities

  • •Design and evolve user and API key authentication flows (SSO/SAML, OAuth, session handling) to keep auth secure and frictionless.
  • •Architect fine-grained authorization for enterprise structures, building RBAC/ABAC and scoped access controls.
  • •Build billing infrastructure that converts trace events into accurate, real-time usage metering and invoicing, including plan management and entitlements.
  • •Create clean, well-documented internal platform APIs for auth and billing so product engineers can ship without permission-check or billing-edge-case concerns.
  • •Ensure seamless integration for self-hosted deployments, including support for enterprise identity stacks (LDAP, OIDC, SAML).

Pay and Benefits

Salary: EUR 90,000 - 160,000 annually
Equity and Bonus:Equity

Key Requirements

  • •Experience building authentication/authorization systems, including SSO/SAML, OAuth, RBAC, and API key management.
  • •Familiarity with billing or payments infrastructure such as usage-based metering, payment provider integrations (Stripe or similar), and entitlements.
  • •Comfort designing secure, reliable platform backend systems with attention to security, edge cases, and failure modes in multi-tenant environments.
  • •Ability to write and reason about TypeScript (backend) and SQL.
  • •Self-driven approach with strong opinions about API design, system boundaries, and safe shipping of shared infrastructure.
Experience:Open sourceSaaSFintechSelf-hosted
Skills:Security-mindedAPI designSystem designSelf-directedAccountability
Tech Stack:TypeScriptNext.jsExpressPostgreSQLClickHouseS3RedisSQLOAuthSSOSAMLRBACABACLDAPOIDCDockerStripeLinearGitHub

Company Brief

Langfuse
Provides an observability and analytics platform for large language models and AI applications, enabling teams to track, debug, and improve model outputs, prompts, and user interactions across deployments.
Industry: Developer Tools
Company Size: Small (11 to 50 employees)
Growth: Early Stage Startup
Funding: Seed
Website