Senior Backend / Platform Engineer

Causa Prima · Madrid

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You'll own the platform our agents run on — event-driven architecture, data pipelines, integrations with customer accounting systems, and the infrastructure that makes everything reliable, auditable, and fast.

What you'll do

• 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.

What we're looking for

• 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.

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