Principle Platform Engineer - Backend Production Expert in London

What this person will build

• A single-node on-prem control plane deployable into a customer environment.
• APIs used by the portal, watchdog, connector layer and detection engine.
• A Postgre SQL-backed data model that can evolve towards the full Merkle Ledger, Trust Contract and Audit architecture.
• A secure event pipeline from watchdog/connector signals through alert generation and response workflows.
• The first hash-chained audit log and evidence export primitives needed for enterprise review.

Backend services for zones, assets, phantoms, alerts, response state, contracts, audit events and evidence generation.

• Core responsibilities
• Translate the Praesidius engineering specification into a pragmatic POC architecture and implementation plan.
• Design and build backend services, APIs and internal module boundaries for the on-prem control plane.
• Own the Postgre SQL schema for assets, zones, phantoms, alerts, response state, policies, audit records and early trust contract objects.
• Build robust ingestion and processing paths for watchdog events, phantom interactions, connector data and response actions.
• Implement authentication, authorisation and RBAC foundations in collaboration with the CTO and frontend engineer.
• Implement the first audit-chain primitives: structured audit entries, predecessor hashing, chain head signing hooks and evidence export APIs.
• Create engineering standards for code quality, testing, error handling, logging, security review and documentation.
• Work with the infrastructure engineer to package the control plane as an on-prem Docker Compose deployment with a clear path to Kubernetes later.
• Work with the detection engineer to ensure alert and response workflows are deterministic, recoverable and explainable.
• Support investor, design partner and Catapult/Innovate UK technical conversations where backend architecture or implementation credibility is relevant.

Required experience

• 8+ years of professional software engineering experience, including ownership of production backend systems.
• Expert-level Python engineering experience. Fast API, Pydantic, asyncio, SQLAlchemy or equivalent frameworks are highly relevant.
• Strong Postgre SQL experience, including schema design, migrations, indexing, transactional semantics and operational performance.
• Experience designing secure APIs and backend systems that need to be reliable, observable and auditable.
• Experience with Docker-based deployments and practical Linux systems engineering.
• Strong understanding of distributed-system trade-offs, even though the first POC is intentionally single-node.
• Ability to write clear technical documentation, decision records and implementation plans.
• Comfortable working in a small founding team where architecture, code, debugging, customer context and hiring input all overlap.

Desirable experience

• Cybersecurity product experience in EDR, XDR, SIEM, SOAR, Zero Trust, identity security, network security or deception technology.
• Experience implementing cryptographic data structures, signed records, PKI integrations or tamper-evident audit systems.
• Experience with Microsoft security ecosystems such as Defender for Endpoint, Microsoft Graph, Entra ID or Sentinel.
• Experience building on-prem enterprise software, appliances or products that run inside customer-controlled environments.
• Previous founding engineer or technical lead experience in an early-stage company.
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