Just like it ensured reliability during small transactions. Customers don't tolerate mistakes when handling their money, so it doesn't matter whether it's a $1 transaction or a $1 million transaction. The reliability of fintech systems rests on three pillars - testing, monitoring and deduplication. Testing allows you to prevent bugs from appearing in a new release. Monitoring facilitates their timely detection, and deduplication saves you from losing money. It is better not to carry out a transaction than to have it repeated several times.