Platform Engineer, AI Security Platform — Hybrid London

Refractal Ltd; Greater London; Hybrid; GBP 110,000 - 170,000; Full time

Benefits offered by this job

Visa sponsorship

London-based office

Equity

Performance bonus

Job summary

Refractal Ltd, a London-based AI security company, seeks a product-minded platform engineer to own core APIs and SDKs from data model to customer integration. You will build and operate enforcement services, authentication layers, and multi-tenant controls while collaborating with founders and early customers.

Key contributions include API design, versioning, and secure customer interfaces, plus building real‑time data streams and a tamper-evident audit ledger.

Qualifications

• Strong backend experience with HTTP APIs; Python and FastAPI experience is preferred.
• Experience with observability, tracing, relational databases, and database migrations.
• Sound judgement around API design, versioning, SDKs, and compatibility.
• A strong understanding of authentication, authorisation, API keys, and multi-tenant access control.
• Good JavaScript and React skills for building operator-facing product surfaces.
• The ability to work independently and own technically uncertain customer problems.

Responsibilities

• Own stable, versioned platform APIs and SDKs, including client interfaces, compatibility rules, documentation, and examples.
• Build FastAPI services for enforcement decisions, evidence, policies, and red-team results.
• Design authentication, sessions, API keys, authorisation, and rigorous multi-tenant isolation.
• Build data and event interfaces, real-time streams, and a tamper-evident audit ledger.
• Create customer onboarding, policy integration, and operator dashboard workflows.
• Own testing and deployment across API compatibility, browser smoke tests, Cloud Run, and Cloud SQL.

Skills

Python

FastAPI

HTTP APIs

Observability

Relational databases

Database migrations

API design

Authentication

Authorization

API keys

Multi-tenant access control

JavaScript

React

Independent work

Tools

Cloud Run

Cloud SQL

Job description

Refractal Ltd, a London-based AI security company, seeks a product-minded platform engineer to own core APIs and SDKs from data model to customer integration. You will build and operate enforcement services, authentication layers, and multi-tenant controls while collaborating with founders and early customers.

Key contributions include API design, versioning, and secure customer interfaces, plus building real‑time data streams and a tamper-evident audit ledger.