case study · 2025

LearnHub

// runs on my machineSource

A full-featured learning management system on the MERN stack.

MongoDB
Express
React
Node.js
Stripe
Razorpay
BullMQ

Problem

An LMS has to juggle payments, role-based access, progress tracking, and notifications — all reliably, across many concurrent learners.

Approach

Role-based access control gates every route. Payments run through Stripe and Razorpay with BullMQ queues handling webhooks and side-effects (certificates, emails) off the request path.

Architecture

RBAC auth: student / instructor / admin scopes
Stripe + Razorpay payments, BullMQ job queue for webhooks
Course progress tracking & certificate generation
Email notifications, Q&A, reviews, and notes modules

Results

Reliable payment + fulfillment flow decoupled via queues
Rich learner features without blocking the request lifecycle

Payments

Stripe + Razorpay

Queue

BullMQ

Access

RBAC

// code

learnhub.ts

// Keep checkout fast: enqueue side-effects, return immediately
router.post("/checkout", auth, rbac("student"), async (req, res) => {
  const order = await Order.create({ user: req.user.id, ...req.body });
  await paymentQueue.add("fulfil", { orderId: order.id }, {
    attempts: 5, backoff: { type: "exponential", delay: 2000 },
  });
  res.status(201).json({ id: order.id, status: "processing" });
});

lessons learned

Decouple webhooks/emails into a queue so the request path stays fast.
Idempotent job handlers make payment retries safe.
Model roles as scopes early — retrofitting RBAC is painful.