| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| crypto/tls | Package tls partially implements TLS 1.2, as specified in RFC 5246, and TLS 1.3, as specified in RFC 8446. |
| crypto/x509 | Package x509 implements a subset of the X.509 standard. |
| encoding/pem | Package pem implements the PEM data encoding, which originated in Privacy Enhanced Mail. |
| errors | Package errors implements functions to manipulate errors. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| net | Package net provides a portable interface for network I/O, including TCP/IP, UDP, domain name resolution, and Unix domain sockets. |
| net/url | Package url parses URLs and implements query escaping. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| strconv | Package strconv implements conversions to and from string representations of basic data types. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| time | Package time provides functionality for measuring and displaying time. |
| unicode | Package unicode provides data and functions to test some properties of Unicode code points. |