Fault tolerance is a crucial aspect of building robust software development kits (SDKs) that can handle transient errors, network issues, and server failures. A well-designed SDK should anticipate these issues, provide clear error messages, retry failed requests when necessary, surface actionable error messages, avoid crashing the host application, and offer fallback behavior where possible. Common pitfalls in SDK design include relying on ideal network conditions, underestimating environmental unpredictability, failing to implement retries, throwing generic or silent failures, tightly coupling API responses, neglecting offline or flaky network conditions, and not accounting for developer-friendly errors. To build more resilient SDKs, developers should adopt best practices such as implementing retries with exponential backoff, graceful degradation, timeouts, cancellation, circuit breakers, and providing clear error messages. By doing so, they can ensure their SDKs handle failure gracefully, improve reliability and user experience, and reduce support requests and development cycles for consumers.