Straight Deal - Car Selling Workflow
Backend Infrastructure by Odama
Production
Project Access
*Code details are confidential and not publicly shared due to client and security restrictions.
About The Platform
Straight Deal is a production-grade car-selling platform built to make vehicle transactions fast, secure, and transparent. As the Full Backend Engineer for this project, I worked directly with the client to translate complex business requirements into a robust infrastructure. The platform handles everything from vehicle data submission and automated valuation to a two-way negotiation flow between users and administrators.
Engineering Excellence: Backend Architecture
Express.js Backend
Monolith architecture with a clean Layered Structure (Controller - Service - Repository). Robustly handles 72 API endpoints with full TypeScript type safety.
Automated Cron Jobs
Scheduled workers manage automated follow-up emails, track offer expirations, and trigger system-wide notifications for both users and admins.
Bidding Workflow
Features
Bidding & Negotiation
A sophisticated two-way negotiation flow between users and admins with price locking.
Automated Follow-up
7-stage automated pipeline managing emails, calls, and texts based on user activity.
Identity Verification
Integration with Persona for automated KYC and ID verification of car owners.
Advanced Car Valuation
Calculates prices based on VIN, mileage, accident history, and 20+ condition markers.
Multi-View Media System
Structured car image upload pipeline for front, rear, and interior condition verification.
Admin Internal Notes
Collaborative notes system for administrators to track submission progress and internal flags.
Role-Based Access (RBAC)
Strict permission isolation between Users, Admins, and Visitors.
OTP & Secure Auth
Hybrid authentication system with Google OAuth2 and secure Twilio SMS OTP.
Challenges
The primary challenge was managing shifting requirements in a live production environment. Working directly with a client without a technical PM meant I had to handle technical translations and implement rapid schema changes while maintaining data integrity for 1,400+ users. I solved this by implementing a rigorous Prisma migration strategy and a layered backend architecture that allowed for modular changes without breaking existing flows. Additionally, optimizing database connections for serverless deployment on Vercel required careful connection pooling management to handle concurrent traffic spikes during bidding sessions.
Technology Stack
- Express.js
- TypeScript
- Prisma ORM
- Layered Architecture
- JWT / Google OAuth2
- Twilio SMS (OTP)
- SendGrid Email
- Persona (KYC)
- Supabase (PostgreSQL)
- Vercel Serverless
- Cron Jobs
- Nginx & Docker
Key Stack
Express.js, TypeScript, Prisma ORM, Supabase PostgreSQL, JWT, Google OAuth2, Twilio, SendGrid, Vercel, Docker.