How the interviewer opens it
“Design a loan origination platform that manages applications through verification, underwriting, approval, and disbursement. The platform must coordinate external providers and long waits without disbursing a loan twice.”
The prompt is vague on purpose. The first minutes are for you. Reduce the prompt to the core features and agree on the numbers before you draw.
What to clarify first
- Loan product
- Scale
- Read and write mix
- Checks and duration
- Latency
- Consistency and availability
- External providers
- Durability and history
- Application changes and decisions
- Deployment and exclusions
The interviewer has the answers. In a SysRound round, Alex gives these answers, as a real interviewer does.
Scope of a strong answer
Core requirements
- Accept applications and track their progress
- Coordinate external checks and manual review
- Approve or reject applications under supplied rules
- Disburse each approved loan without duplicate transfers
Usually out of scope
- Repayment and collections
- Credit model development
- The bank's transfer system
- Partial disbursements and multiple currencies
What interviewers ask about
- Application progress
- Applications wait for days while workers fail and providers repeat results. The platform must resume work without losing progress.
- Approval validity
- Applicants and reviewers can change the same application while checks remain active. A valid approval must refer to the exact facts that authorize payment.
- Disbursement outcomes
- The database and bank cannot share one transaction. A timeout leaves an unknown outcome, and a new transfer attempt can pay twice.
Common mistakes
- Keeps a database transaction open during an external call
- Assumes a timeout proves that no transfer occurred
- Uses retries without stable request identities
- Ignores application changes while checks and reviews remain active
- Treats workflow state as a complete financial or decision history
- Adds many services despite modest throughput and closely related state
The bar by level
- Senior (L5/E5)
- Makes workflow recovery concrete. Preserves acknowledged changes across an availability zone failure. Handles duplicate callbacks, stale decisions, and concurrent payouts. Uses transactions and bank deduplication.
- Staff (L6+/E6+)
- Defines guarantees across the bank boundary. Handles contract limits, operator recovery, policy changes, and regional failure. Connects audit evidence and security controls to business invariants.