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Hisaab

building

WhatsApp receivables autopilot for MSMEs

Next.jsWhatsAppBullMQRedisRazorpay

the problem

Indian MSMEs collectively hold ₹20L+ crore in outstanding receivables. Chasing payments is done manually — phone calls, WhatsApp messages — consuming hours every week. Most small businesses have no collections system.

market context

WhatsApp is how India does business. UPI is how India pays. Hisaab connects these: automated WhatsApp reminders with direct UPI payment links, sent on a schedule the MSME controls. CAs are the distribution channel — each CA handles 10–100 MSME clients.

how it's built

Next.js frontend with Supabase for auth and invoice data. BullMQ + Redis for the reminder job queue — delayed jobs, retry logic, backoff. WhatsApp Business for delivery. Razorpay for UPI link generation. The worker runs on Railway, separate from the Vercel frontend.

architecture

MSMEadds invoiceNext.js+ SupabaseBullMQRedis queueWhatsAppBusiness APIcustomerUPI link

tech stack

frontend
Next.js 16Tailwind CSS
backend
SupabaseBullMQRedis
data
Supabase (PostgreSQL)
infra
Vercel (frontend)Railway (BullMQ worker)WhatsApp Business

outcomes

  • →152 tests passing across all modules
  • →Full WhatsApp → scheduled reminders → UPI payment flow built
  • →24 commits, code complete