SaaS Virtual Trading Platform

—Job Description
We are building a backend-heavy white-label SaaS trading platform (simulated / virtual trading only, not real-money brokerage) and are looking for a senior full-stack developer to build the core system end-to-end.
This is NOT a basic CRUD application.
The project involves ledger systems, risk management, margin logic, WebSockets, and multi-tenant SaaS architecture.
— Core Responsibilities
You will be responsible for designing and building the following systems:
Core Platform
Multi-tenant SaaS with strict firm_id based data isolation
White-label custom domain mapping
Role system: Super Admin, Firm Admin, Broker, User
JWT authentication with RBAC
Transaction password (T-Pass) for sensitive actions
Trading Engine (Simulated)
Virtual order engine (Market, Limit, SL, SL-M)
Margin blocking and release
Position lifecycle and PnL calculation
Auto square-off on loss threshold
Profit lock and cooldown logic
SL and TP execution based on live prices
Wallet and Ledger (Critical)
Virtual wallets for User, Broker, and Admin
Immutable append-only ledger
No update or delete of ledger entries
Reversal-based corrections only
Fully atomic database transactions
Risk Management System (RMS)
Max lots per order
Max open positions
Max exposure
Daily loss limit
RMS enforcement before order placement
Real-Time Systems
Price feed integration (Kite, Alltick, or similar)
WebSocket streaming to clients
Redis for caching and pub/sub
Reporting and Audit
Trade, order, and position reports
Wallet and ledger reports
Immutable audit logs
CSV and PDF export
—Preferred Tech Stack
Backend
Node.js with Express or Laravel
PostgreSQL (ACID transactions mandatory)
Redis
WebSockets
REST APIs
Infrastructure
NGINX
HTTPS / SSL
Domain mapping
Cloudflare preferred
Frontend
React (basic dashboards only; UI is not the main focus)
—Required Experience
4 or more years of full-stack development experience
Strong backend and database fundamentals
Experience with financial systems, ledgers, wallets, or RMS logic
Comfortable with async processing and WebSockets
Ability to follow a strict SRS (will be provided)
No beginners and no learning-on-the-job profiles.
— Project Duration
4 to 5 months
— Budget
₹2,50,000 INR (fixed price)
Approximately USD 3,000
Payments will be made strictly milestone-based.
— Payment Milestones (High Level)
Architecture design and database schema
Authentication and multi-tenant core
Wallet and ledger engine
Trading engine and RMS
Frontend panels and reports
Final hardening and documentation
No advance payment without completed deliverables.
— To Apply, Please Include
Similar backend-heavy projects (GitHub links preferred)
Experience with ledger, wallet, trading, or RMS logic
Which stack you recommend (Node or Laravel) and why
Confirmation that you can work with milestone-based payments
Estimated weekly availability
—Important Notes
This is not a real-money exchange or broker integration
Backend is the single source of truth
Ledger and audit logs must remain immutable
Code quality is more important than speed
Weekly demos are mandatory