Day 21 of building a financial agent focused on data ingestion. The developer used Plaid Sandbox to simulate bank connections, generating transaction data from a fake institution. This approach allows testing without real financial credentials, crucial for early-stage fintech development.

For live data, the project leveraged Wise's Personal Token API. This provides real-world transaction histories, essential for validating an app's logic. The setup requires installing `plaid-python` and `requests`, highlighting the growing ecosystem of fintech APIs available to developers building financial tools.

A key technical hurdle emerged on macOS: SSL certificate verification failures. The fix involves running Python's Install Certificates.command script. This common issue underscores the practical challenges developers face when integrating external APIs, moving beyond theoretical code to functional, production-ready systems.