Tech

Backend: Node.js, Express.js
Database: PostgreSQL (with UUIDs, pgcrypto, indexing, constraints)
Caching & Queues: Redis (lists, Streams, consumer groups, TTL)
Security: HMAC signing & verification for webhooks
DevOps / Tools: Docker, dotenv, Axios for HTTP requests
Testing / Simulation: Dummy webhook server for failure simulation

Feature

Designed and implemented a multi-tenant webhook delivery system that allows multiple applications to subscribe to events and receive reliable webhook notifications with fault tolerance and retry guarantees. \

✔ Multi-tenant webhook fan-out
✔ Subscription stored in postgres
✔ Redis cache
✔ Redis Streams for delivery queue
✔ Consumer group based workers
✔ Dummy webhook server ready
✔ HTTP delivery with retries
✔ Failure simulation
✔ DLQ after max retries
✔ HMAC signing + verification
✔ Sender-side idempotency via delivery_id
✔ Redis-based sender-side dedupe with TTL
✔ Exponential backoff + jitter

Steps to start the things:

-> npm i // if node_modules are not present in server and dummyServer
-> docker-compose up - d
-> /server -> nodemon server.js
-> /server -> node .\workers\delivery.worker.js
-> /dummyServer -> nodemon server.js