Senior Backend / Platform Engineer

About the Position

Senior Backend / Platform Engineer

Causa Prima is seeking a Senior Backend / Platform Engineer to join our team in Madrid, Spain, or Munich, Germany. You'll be responsible for owning the platform our agents run on, focusing on event-driven architecture, data pipelines, integrations with customer accounting systems, and ensuring the infrastructure is reliable, auditable, and fast.

Responsibilities

• Event store - Append-only PostgreSQL with tamper-evident hash chaining, real-time event distribution, agent replay and recovery, schema versioning.
• Cryptographic signature infrastructure - Key management, signature verification on all agent events, approval chains for external actions.
• Workflow Constraint Engine - The gateway that verifies authorization before any external action (email, payment, API call) proceeds.
• PII Vault & GDPR compliance - Isolated, encrypted storage for personal data. Right to erasure. Data residency per region.
• Multi-tenancy - Row-level security, tenant isolation across all data stores, tenant-scoped LLM API keys.
• Authorization (Cerbos) - Attribute-based access control for agents and humans. Deterministic policy evaluation - LLMs never make auth decisions.
• MCP security layer - Authentication, capability-based scoping per partner, and rate limiting for the Model Context Protocol endpoint.
• Database architecture - PostgreSQL schema design, indexing strategy, performance tuning, read replica topology.

Requirements

• 3+ years experience with Python and/or TypeScript in production.
• 5+ years designing backend platforms for production systems.
• Strong systems design skills - this is the primary requirement. You think in boundaries, contracts, failure modes, and scaling characteristics.
• Deep PostgreSQL knowledge - RLS, indexing tradeoffs, event sourcing patterns, schema evolution.
• Strong application security architecture skills: encryption models, key management, auth patterns.
• Experience with policy-as-code authorization (Cerbos, OPA, Cedar, or similar).
• Strong code review skills for security-sensitive AI-generated code.

Nice to Have

• Cryptographic primitives in production (digital signatures, hash chaining, application-layer encryption).
• Event streaming platforms (Kurrent, Redpanda, Kafka).
• SOC 2 or GDPR compliance engineering.
• Fintech or regulated-environment background.

We Offer

• Location: Madrid, Spain; Munich, Germany
• Employment Type: Full-time, On-site
• Department: ENGINEERING

About the Company

At Causa Prima, we are dedicated to building secure and reliable platforms for our clients. Our team is passionate about creating innovative solutions that meet the highest standards of security and performance.