Design account opening workflow
Overview
This question evaluates a candidate's ability to architect a high-scale, secure, and regulated online account opening workflow, including API design, workflow orchestration, data modeling, PII protection, KYC/AML and sanctions integration, auditability, and operational reliability.
Coinbase
Sep 6, 2025, 12:00 AM
Software Engineer
Take-home Project
System Design
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System Design: Online Bank Account Opening Workflow
Context
You are designing a high-scale online bank account opening workflow for web and mobile clients. The system must operate in a regulated environment, integrate with external KYC/AML and sanctions providers, and provide a secure, resilient, and auditable experience across multiple regions.
Requirements
Design the following:
- APIs
- Start a new application, save partial progress, submit, and resume an application.
- Upload documents and verify them.
- Provide real-time application status.
- Workflow orchestration
- Which steps are synchronous vs. asynchronous, and why.
- How to model long-running tasks, callbacks, and manual review.
- Correctness and safety
- Idempotency and deduplication to prevent duplicate accounts.
- Failure handling, retries, and exactly-once or at-least-once guarantees where appropriate.
- Audit trails sufficient for regulatory compliance.
- Data and security
- Data model for Applicants, Applications, Documents, and related entities.
- PII security: encryption, key management, access control, and safe logging.
- Rate limiting and abuse controls.
- Risk and compliance
- KYC/AML and sanctions checks (and re-checks as needed).
- Fraud/risk scoring and decisioning (auto-approve, reject, manual review).
- Scale and reliability
- Scale to millions of applications per day.
- Multi-region architecture and data residency.
State any minimal assumptions you make.
Solution
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