Methodology
How we examine a payment API estate — from trust boundaries to evidence your compliance team can reuse.
Inventory the money-moving surface
We catalogue gateways, tokenisation services, payout endpoints, merchant onboarding APIs, and webhook receivers that can create, change, or confirm financial state. Shadow and deprecated hosts are included when traffic or DNS still points to them.
Map trust boundaries and credentials
Each surface gets a trust model: who authenticates, what scopes apply, where secrets live, and which partner credentials can reach production. Broken assumptions here drive most high-severity findings.
Sample live controls
We sample authentication flows, rate limits, signature checks, logging, and key rotation evidence from a recent period. Sampling shows whether documented controls operate under load, not only in design decks.
Trace abuse and failure paths
We walk forged webhooks, replayed events, over-scoped tokens, and error responses that leak sensitive state. The goal is concrete impact language — not a generic vulnerability catalogue.
Sequence remediation
Findings are ranked by fund-movement risk and operational feasibility. You receive must-fix items first, then structural improvements, with named owners where we can identify them during the engagement.