infospace-bench/infospaces/patterns-of-it-securita-architecture/artifacts/entities/pattern-schema-first-api-security.md

Pattern: Schema-First API Security

Status: seed Readiness target: RL3 production Primary owners: product repos, NetKingdom Genesis family: Application/API security

Problem

APIs become difficult to validate, test, and protect when the request and response contract is implicit.

Context

Use this pattern for OpenAPI, async APIs, event schemas, public APIs, tenant APIs, and internal service contracts.

Forces

• Schemas can drive validation and tests.
• Schemas alone do not prove authorization.
• Backward compatibility must be managed.
• Sensitive fields need explicit treatment.

Solution

Define API schemas before or alongside implementation and use them to drive validation, compatibility checks, security tests, documentation, and gateway/application enforcement.

Verification

• Requests and responses are validated against versioned schemas.
• Sensitive fields are marked and tested.
• Breaking changes are detected before release.
• Authorization tests cover resources described by the schema.

Related Patterns

• API Gateway as Security Boundary.
• Object-Level Authorization Check.
• Backend-for-Frontend.
• Secure File Upload Pipeline.