| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| os/user | Package user allows user account lookups by name or id. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |