Billstream: Payments QA for a Fast-Moving Fintech

Billstream is a B2B payments platform processing millions of dollars in transactions monthly. When a production bug in their invoicing flow caused double-charges for several enterprise clients, they needed immediate expert help.

STS was engaged within 48 hours. We ran a rapid triage, identified the root cause (a race condition in their payment state machine), and rebuilt their payment flow test suite to catch similar edge cases.

Beyond the immediate fix, we implemented a comprehensive fintech QA framework: transaction boundary testing, reconciliation verification, multi-currency edge cases, and performance testing under peak load.

Results: Zero payment incidents in the 12 months following our engagement. SOC 2 Type II audit passed with no QA-related findings.