> For the complete documentation index, see [llms.txt](https://docs.serverlessapigateway.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.serverlessapigateway.com/glossary/f/fault-tolerance.md). # Fault Tolerance Fault tolerance is the ability of a system to continue functioning correctly even when one or more of its components fail. A fault-tolerant system is designed to detect failures, isolate the faulty component, and continue operating -- possibly with reduced capacity -- without affecting the end user's experience. Techniques for achieving fault tolerance include redundancy (running multiple instances of a component), replication (maintaining copies of data across nodes), health checks (detecting failed components), and circuit breakers (preventing cascading failures by stopping requests to unhealthy services). Graceful degradation is a related concept where a system provides reduced functionality rather than complete failure. In API gateway and serverless architectures, fault tolerance is built into the platform at multiple levels. Edge-deployed gateways automatically route around failed nodes. Serverless functions are typically stateless and can be restarted instantly on healthy infrastructure. API gateways can implement retry logic, timeouts, and fallback responses to handle failures in upstream services, shielding clients from transient backend issues. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.serverlessapigateway.com/glossary/f/fault-tolerance.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.