Suhag
Web developer
Trade Link Network
Project Overview
A UK-focused leads marketplace platform that connects homeowners looking for trade services with local professionals (plumbers, electricians, roofers, etc.).
Core Features
- Pay-per-lead UK tradesperson marketplace matching customers with local professionals.
- Free customer job posting with dynamic questions and multi-channel verification.
- Geo-radius matching limit searches and locked budget pricing.
My Contributions
- Designed and built the entire modular feature-based backend using Node.js, Express, and TypeScript.
- Implemented postcode-based geographic matching and working radius limit logic.
- Integrated Stripe payments and webhooks with dynamic, locked lead pricing calculations.
- Configured SMS and email verification flows using Twilio and Nodemailer.
- Created a comprehensive admin dashboard to manage users, pricing, reviews, and transactions.
Key Challenges & Solutions
Challenge:
Calculating geographic radius limits and postcode matching in real-time without hurting database query performance.
Solution:
Utilized MongoDB 2dsphere geospatial indexes and $nearSphere queries, combined with caching UK postcode coordinates in Redis.
Challenge:
Preventing race conditions where multiple professionals try to purchase the same lead concurrently.
Solution:
Implemented pessimistic locks using Redis-based lock tokens, ensuring that a lead's purchase limit of 3 is strictly enforced under high load.
Challenge:
Handling webhook payment failures or user disconnects during Stripe checkout.
Solution:
Created an idempotent Stripe webhook processing system with transactional rollbacks in MongoDB, ensuring job status integrity.
Tech Stack
TypeScriptNode.jsExpress.jsMongoDBMongooseRedisSocket.ioStripeNext.jsTwilio sms