Feeny
Causa Prima

Senior Backend / Platform Engineer at Causa Prima (Madrid, Spain)

Causa Prima· Madrid, Spain·

Role details

Work type
Onsite
Employment
Full-Time
Skills
PythonTypeScriptPostgreSQLSystems DesignEvent SourcingApplication Security ArchitectureEncryption ModelsKey ManagementAuth PatternsPolicy-as-codeCerbosOPA

Summary

Design and build the event-driven platform for AI agents, focusing on PostgreSQL event storage, cryptographic signature infrastructure, and multi-tenancy. The role involves implementing authorization gateways, PII vaults, and secure database architecture to ensure reliability, audibility, and GDPR compliance.

Job description

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.

Why work at Causa Prima

  • Culture: Described by founders as a “once-in-a-lifetime opportunity” for people who want to build high-impact infrastructure from scratch. Emphasis on entrepreneurial drive and solving a problem that software has never fully addressed.
  • Remote/Hybrid/Office: Presence in Madrid and Munich; roles appear to be in-office or hybrid (engineering roles listed in these cities).
  • Notable perks/engineering culture: Early-stage startup with a small team (6 employees as of mid-2026) — high ownership and direct impact. Tech stack includes TypeScript, GraphQL, PostgreSQL, Redis, Terraform, Kubernetes, and Python. Open-source contributions (Scribo) are a core part of the product strategy. Backed by top-tier VC (Creandum) with strong founder track record.

Application questions