Package httpcache provides an implementation of http.RoundTripper that adds transparent HTTP response caching according to RFC 9111 (HTTP Caching). The main entry point is NewTransport, which returns an http.RoundTripper for use with http.Client. httpcache supports the required standard HTTP caching directives, as well as extension directives such as stale-while-revalidate, stale-if-error and immutable. Example usage: