The **aws-sdk-client-mock** library provides a typed, fully‑featured mocking layer for AWS SDK v3 JavaScript/TypeScript clients, letting developers intercept and stub command calls (e.g., S3, DynamoDB, SNS) with fluent configuration, strict input matching, spies, and Jest/Vitest matchers. It is aimed at engineers who need reliable unit‑test isolation for AWS‑integrated code—especially those using the modular SDK v3, TypeScript projects, and testing frameworks like Jest or Vitest.