Senior Firebase/Google Cloud Backend API Architect

We are seeking a senior Firebase/Google Cloud backend architect to review and optimize an existing API. The role involves enhancing performance, security, and scalability of the API, which is built with Firebase Authentication, Firestore, and Cloud Functions. The ideal candidate will have experience in designing and implementing cloud-based systems and a strong understanding of Firebase and Google Cloud technologies. We already have a working initial API, but we need expert help to make it faster, more rugged, more secure, and easier to maintain over time. Scope: * Review current API architecture, backend code, and data flow * Review Firestore data model, queries, indexes, performance, and cost risks * Review Firebase Auth, Admin SDK usage, custom claims, and Security Rules * Identify bottlenecks, security risks, scaling issues, and maintainability concerns * Recommend whether to continue with Cloud Functions, move some services to Cloud Run, or use a hybrid approach * Optimise key API paths where needed * Improve logging, monitoring, error handling, deployment setup, and operational management * Provide a prioritised improvement plan with time estimates * Support GDPR / European privacy compliance, including secure deletion of user data on request Required experience: * Firebase / Google Cloud backend architecture * Firestore performance optimisation * Firebase Auth and Security Rules * Cloud Functions v2 and/or Cloud Run * TypeScript / Node.js backend development * Production API performance, security, monitoring, and maintenance * GDPR-compliant data handling and user data deletion We are not looking for a generalist Firebase app developer. We need someone with deep experience reviewing, designing, and optimising production APIs. Please include examples of Firebase / Firestore APIs you have improved, and briefly explain what you optimised.