Design Groww

Design a stock trading and investment platform like Groww that enables users to buy/sell stocks and mutual funds in real-time. The system handles user onboarding with KYC, streams real-time market data to millions of concurrent users via WebSocket, manages order placement and routing to stock exchanges (NSE/BSE) via FIX protocol, maintains a double-entry funds ledger with T+1 settlement, computes real-time portfolio P&L, supports mutual fund investments with SIP scheduling, and ensures regulatory compliance (SEBI) with complete audit trails.

Scale Estimates

Metric	Value
Registered users	100 million
Daily active users	10 million
Concurrent users (market hours)	5 million
Orders per day	50 million
Orders per second (peak, market open)	100,000
Listed instruments (equities + F&O)	5,000+
Real-time ticks per second (from exchange)	50,000+
WebSocket connections (concurrent)	5 million
Mutual fund SIPs active	20 million
Daily trading volume	₹50,000 crore+

Non-Functional Requirements

Low latency: Order placement to exchange acknowledgement < 100ms; market data tick to user display < 500ms; portfolio P&L update on every price tick (client-side computation)
Reliability: OMS is mission-critical — zero order loss; WAL + synchronous replication; RTO < 30s; exchange gateway primary + standby; no trade data discrepancy
Consistency: Funds ledger requires ACID (double-entry accounting); fund blocking prevents over-ordering; PostgreSQL with serializable isolation for critical transactions
Scalability: 10× traffic spike at market open (9:15 AM); pre-warming; Kafka for order queue absorption; auto-scaling WebSocket gateways; read replicas for portfolio queries
Compliance: SEBI regulations; KYC verification (Aadhaar/PAN); contract notes for every trade; tax reporting (STCG/LTCG); complete audit trail; daily reconciliation (internal vs exchange vs bank)
Security: 2FA for login + transactions; encrypted data at rest and in transit; PCI DSS for payment data; demat account security; fraud detection (unusual trading patterns)

Scale Estimates

Metric

Value

Registered users

100 million

Daily active users

10 million

Concurrent users (market hours)

5 million

Orders per day

50 million

Orders per second (peak, market open)

100,000

Listed instruments (equities + F&O)

5,000+

Real-time ticks per second (from exchange)

50,000+

WebSocket connections (concurrent)

5 million

Mutual fund SIPs active

20 million

Daily trading volume

₹50,000 crore+

Non-Functional Requirements

Low latency: Order placement to exchange acknowledgement < 100ms; market data tick to user display < 500ms; portfolio P&L update on every price tick (client-side computation)

Reliability: OMS is mission-critical — zero order loss; WAL + synchronous replication; RTO < 30s; exchange gateway primary + standby; no trade data discrepancy

Consistency: Funds ledger requires ACID (double-entry accounting); fund blocking prevents over-ordering; PostgreSQL with serializable isolation for critical transactions

Scalability: 10× traffic spike at market open (9:15 AM); pre-warming; Kafka for order queue absorption; auto-scaling WebSocket gateways; read replicas for portfolio queries

Compliance: SEBI regulations; KYC verification (Aadhaar/PAN); contract notes for every trade; tax reporting (STCG/LTCG); complete audit trail; daily reconciliation (internal vs exchange vs bank)

Security: 2FA for login + transactions; encrypted data at rest and in transit; PCI DSS for payment data; demat account security; fraud detection (unusual trading patterns)

Scale Estimates

Non-Functional Requirements

Functional Requirements

Approach Guide(Click to expand each section)

Follow-up Deep Dives(Questions an interviewer might ask)

Design Groww

Scale Estimates

Non-Functional Requirements

Functional Requirements

Approach Guide(Click to expand each section)

Follow-up Deep Dives(Questions an interviewer might ask)

Design Groww

Scale Estimates

Non-Functional Requirements

Functional Requirements

Approach Guide(Click to expand each section)

Non-Functional Requirements~3 min

Core Entities~2 min

API Design~3 min

High-Level Design~5 min

Follow-up Deep Dives(Questions an interviewer might ask)

1How would you design the order management system (OMS)?

2How would you handle real-time market data distribution?

3How would you design the funds and settlement system?

4How would you ensure reliability during high-traffic market events?

5How would you design the portfolio and P&L computation?

6How would you design the system for mutual fund investments?

7How would you architect the system end-to-end for scale and reliability?

Key Topics

Asked At

Design Groww

Scale Estimates

Non-Functional Requirements

Functional Requirements

Approach Guide(Click to expand each section)

Non-Functional Requirements~3 min

Core Entities~2 min

API Design~3 min

High-Level Design~5 min

Follow-up Deep Dives(Questions an interviewer might ask)

1How would you design the order management system (OMS)?

2How would you handle real-time market data distribution?

3How would you design the funds and settlement system?

4How would you ensure reliability during high-traffic market events?

5How would you design the portfolio and P&L computation?

6How would you design the system for mutual fund investments?

7How would you architect the system end-to-end for scale and reliability?

Key Topics

Asked At