Notifyflow is a multi-tenant notification delivery platform that lets developers send email, webhook, in-app, and SMS notifications through a single API call — without building any of the underlying infrastructure themselves.
Built as a deep learning project inspired by Novu, Courier, and Knock, it handles everything a production notification system needs: async job queuing, priority-based delivery, exponential backoff retries, a dead-letter queue for permanent failures, per-tenant rate limiting, and a real-time delivery dashboard.
Key engineering decisions:
→ Three priority BullMQ queues so OTPs never wait behind bulk campaigns
→ Atomic sliding window rate limiter using a Redis Lua script to eliminate race conditions
→ Bring Your Own Keys (BYOK) — tenants connect their own Resend account, credentials stored encrypted with AES-256-GCM
→ Redis Pub/Sub bridges the API and worker processes, streaming live delivery events to the dashboard via SSE
→ Strategy pattern for channel abstraction — adding a new provider is one new class, zero changes to the pipeline