| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| io | Package io provides basic interfaces to I/O primitives. |
| io/ioutil | Package ioutil implements some I/O utility functions. |
| net | Package net provides a portable interface for network I/O, including TCP/IP, UDP, domain name resolution, and Unix domain sockets. |
| net/http | Package http provides HTTP client and server implementations. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| sync | Package sync provides basic synchronization primitives such as mutual exclusion locks. |
| syscall | Package syscall contains an interface to the low-level operating system primitives. |