Senior Backend & Production Engineer Replit / Node.js/TypeScript / PostgreSQL: Self-Development App

FRQNCY is a live AI-powered identity transformation app with thousands of paying users. The product helps users identify subconscious blocks, understand the gap between their current identity and Future Self, and stay consistent through personalised onboarding, AI-generated insights, Future Self guidance, recalibration tools, daily tasks, notifications and progress tracking. We are hiring a Senior Backend & Production Engineer to take ownership of the existing FRQNCY backend, improve reliability, reduce technical risk and progressively clean up the architecture without disrupting the live product. This is not a greenfield rebuild. Your first job is to understand what already works, preserve production behaviour, and then turn the current backend into a safer, cleaner and more dependable production system. Our current stack includes Node.js 20, TypeScript, Express 5, PostgreSQL 16, Drizzle ORM, Replit Autoscale, Stripe, RevenueCat, Supabase authentication, OneSignal, Beehiiv, AgentMail and multiple AI providers including Anthropic, Gemini and DeepSeek. The backend is a substantial production system with roughly 65 database tables and a large existing TypeScript codebase. FRQNCY_Hiring_Roles_Backend_and_Product_Engineer.pdf You will be responsible for taking primary ownership of the backend, improving PostgreSQL integrity and performance, introducing safer database migrations, improving background job reliability, hardening authentication and authorization, improving Stripe and RevenueCat subscription reconciliation, making AI integrations more resilient, improving logging and monitoring, creating proper testing and release processes, and responding quickly to production incidents. FRQNCY_Hiring_Roles_Backend_and_Product_Engineer.pdf You should have strong experience with Node.js, TypeScript, Express, PostgreSQL, production debugging, APIs, Stripe webhooks, subscription systems, authentication, Git/GitHub, database migrations, retries, concurrency and incident response. Experience working inside Replit is highly valuable. FRQNCY_Hiring_Roles_Backend_and_Product_Engineer.pdf We move quickly and use AI coding tools heavily, including tools such as Codex, Claude Code, Kimi and Replit Agent. You should be comfortable using AI as an engineering multiplier while still being able to independently verify, debug and take responsibility for the code that reaches production. FRQNCY_Hiring_Roles_Backend_and_Product_Engineer.pdf This is a high-ownership role working on a live product used by real paying customers every day. We are looking for someone who can identify problems independently, understand root causes and own issues through diagnosis, repair and verification.