Event-driven bank transaction processing pipeline orchestrates data flow from API ingestion through validation using AWS managed services. XXX Service creates header documents in MongoDB with status 100, requests transaction data from Bank API, and conditionally updates status to 900 or saves responses to S3 based on transaction existence. Kafka Topic streams S3 links and transaction metadata to YY Service for downstream validation, demonstrating asynchronous processing patterns critical for financial data integrity and audit trails. This architecture separates concerns between ingestion, storage, and validation while maintaining event-driven scalability for high-volume banking operations. Fork this diagram on Diagrams.so to customize status codes, add error handling queues, or integrate additional validation services for your fintech stack.