B2B Auto-Parts Portal

Problem

The legacy distributor ran on Excel + Zalo + phone calls: garages call → staff checks Excel → quotes → handwrites the order. Wrong codes, sudden stockouts, no purchase history. B2B revenue plateaued.

Architecture

Next.js 15 App Router + RSC → tRPC + Postgres (38k-SKU catalog) → OEM full-text + similarity search (pg_trgm) → VNPT e-invoice + VietQR payment integration → MISA accounting webhook. Real-time stock via SSE from ERP.

Stack & rationale

• Next.js 15 App Router: server components cut bundle ~40%, SSR catalog for SEO.
• pg_trgm over Algolia: catalog isn't huge, local search is good enough and cheaper.
• VietQR: instant B2B payments, T+1 reconciliation.

Results (first 4 months)

Lessons

OEM search must support fuzzy + alias (different makers call the same part by different codes). Cache invalidation for real-time stock via SSE is simpler than WebSocket for one-way data.