In financial settlement infrastructure, an API failure can mean funds stuck in transit, duplicated operations, or regulatory violations. This constraint shaped every design decision for Infracash's API.
Principle 1: Explicit and Versioned Contracts
Each endpoint has an OpenAPI 3.1 contract with typed schemas and automatic validation.
Principle 2: Idempotency by Design
Each write operation accepts an idempotency key. Duplicate requests return the original result without reprocessing.
Principle 3: Structured and Actionable Errors
Each error response includes a unique code, human-readable message, and an "action" field.
Principle 4: Layered Authentication
mTLS for channel authentication and API keys with granular scopes for authorization.
Principle 5: Native Observability
Each request generates a trace ID that follows the operation through all layers.
References: Stripe Engineering Blog, KPMG (2025), Global Payments / Google Cloud (2025).