| archive/zip | Package zip provides support for reading and writing ZIP archives. |
| bytes | Package bytes implements functions for the manipulation of byte slices. |
| context | Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes. |
| encoding/json | Package json implements encoding and decoding of JSON as defined in RFC 7159. |
| expvar | Package expvar provides a standardized interface to public variables, such as operation counters in servers. |
| flag | Package flag implements command-line flag parsing. |
| fmt | Package fmt implements formatted I/O with functions analogous to C's printf and scanf. |
| go/build | Package build gathers information about Go packages. |
| go/format | Package format implements standard formatting of Go source. |
| golang.org/x/sys/execabs | Package execabs is a drop-in replacement for os/exec that requires PATH lookups to find absolute paths. |
| golang.org/x/tools/godoc | Package godoc is a work-in-progress (2013-07-17) package to begin splitting up the godoc binary into multiple pieces. |
| golang.org/x/tools/godoc/redirect | Package redirect provides hooks to register HTTP handlers that redirect old godoc paths to their new equivalents. |
| golang.org/x/tools/godoc/static | Package static exports a map of static file content that supports the godoc user interface. |
| golang.org/x/tools/godoc/vfs | Package vfs defines types for abstract file system access and provides an implementation accessing the file system of the underlying OS. |
| golang.org/x/tools/godoc/vfs/gatefs | Package gatefs provides an implementation of the FileSystem interface that wraps another FileSystem and limits its concurrency. |
| golang.org/x/tools/godoc/vfs/mapfs | Package mapfs file provides an implementation of the FileSystem interface based on the contents of a map[string]string. |
| golang.org/x/tools/godoc/vfs/zipfs | Package zipfs file provides an implementation of the FileSystem interface based on the contents of a .zip file. |
| golang.org/x/tools/internal/gocommand | Package gocommand is a helper for calling the go command. |
| golang.org/x/tools/playground | Package playground registers an HTTP handler at "/compile" that proxies requests to the golang.org playground service. |
| golang.org/x/xerrors | Package xerrors implements functions to manipulate errors. |
| io | Package io provides basic interfaces to I/O primitives. |
| log | Package log implements a simple logging package. |
| net/http | Package http provides HTTP client and server implementations. |
| net/http/pprof | Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool. |
| net/url | Package url parses URLs and implements query escaping. |
| os | Package os provides a platform-independent interface to operating system functionality. |
| path | Package path implements utility routines for manipulating slash-separated paths. |
| path/filepath | Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths. |
| regexp | Package regexp implements regular expression search. |
| runtime | Package runtime contains operations that interact with Go's runtime system, such as functions to control goroutines. |
| strings | Package strings implements simple functions to manipulate UTF-8 encoded strings. |
| text/template | Package template implements data-driven templates for generating textual output. |