Zonely — Two-Sided Expert Marketplace

The complete backend for a two-sided consultation marketplace with live audio sessions, real-time chat and ledger-based billing — greenfield to go-live, built solo.

Scope

I architected and delivered the entire backend alone — from an empty repository to a live product — across 48 database migrations and 390+ merged pull requests.

Zonely architecture: a mobile client calls a Fastify API backed by auth, user, session and transaction services; webhooks and a one-minute reconciliation cron drive the session and transaction services, which use MySQL via Prisma, object storage, and Cashfree, telephony, Firebase, OTP messaging and Aadhaar KYC integrations. — System architecture

The wallet ledger

Balances are derived from an append-only transaction ledger rather than stored in a column. This eliminates write-race conditions between concurrent session charges and top-ups, and keeps the full transaction history as an auditable source of truth.

Session termination

An idempotent dual-path termination flow — webhook-driven for voice calls, client-triggered for chat — with a per-minute reconciliation job as a safety net for missed provider webhooks.

Payment gateway migration

Mid-project I led the migration from Razorpay/RazorpayX to Cashfree across both payment collection and payouts, without disrupting existing payouts and preserving the existing transaction ledger and requiring no changes to session or balance logic. I also shipped a backward-compatible admin refund mechanism that needed no mobile client release.

Integrations

I owned the integration of five external services — Exotel telephony, payments, OTP and messaging, Firebase real-time chat, and Surepass for Aadhaar-based expert KYC.