What difficulties have you faced when developing financial services?

When developing financial services, you often encounter the following challenges:

• Calculation accuracy: using float can lead to rounding errors, so Decimal or specialized libraries are used.
• Ensuring data consistency: transactions must be atomic to avoid balance discrepancies.
• Security and compliance: data protection, encryption, auditing, and regulatory compliance (e.g., PCI DSS).
• Error handling and fault tolerance: financial operations are critical, so reliable failure handling is essential.
• High load and scalability: services must process a large number of operations quickly.

For example, when implementing fee calculations, it is important to consider all rules and exceptions, as well as test on boundary cases to avoid financial losses.