benchmark/parsePackage parse provides support for parsing benchmark results as generated by 'go test -bench'.
blogPackage blog implements a web server for articles written in present format.
blog/atomPackage atom defines XML data structures for an Atom feed.
cmd/benchcmpThe benchcmp command displays performance changes between benchmarks.
cmd/bundleBundle creates a single-source-file version of a source package suitable for inclusion in a particular target package.
cmd/callgraphcallgraph: a tool for reporting the call graph of a Go program.
cmd/coverCover is a program for analyzing the coverage profiles generated by 'go test -coverprofile=cover.out'.
cmd/digraphThe digraph command performs queries over unlabelled directed graphs represented in text form.
cmd/egThe eg command performs example-based refactoring.
cmd/fiximportsThe fiximports command fixes import declarations to use the canonical import path for packages that have an "import comment" as defined by
cmd/godexThe godex command prints (dumps) exported information of packages or selected package objects.
cmd/godocGodoc extracts and generates documentation for Go programs.
cmd/goimportsCommand goimports updates your Go import lines, adding missing ones and removing unreferenced ones.
cmd/gomvpkgThe gomvpkg command moves go packages, updating import declarations.
cmd/gorenameThe gorename command performs precise type-safe renaming of identifiers in Go source code.
cmd/gotypeThe gotype command, like the front-end of a Go compiler, parses and type-checks a single Go package.
cmd/goyaccGoyacc is a version of yacc for Go.
cmd/guruguru: a tool for answering questions about Go source code.
cmd/guru/serialPackage serial defines the guru's schema for -json output.
cmd/heapviewheapview is a tool for viewing Go heap dumps.
cmd/html2articleThis program takes an HTML file and outputs a corresponding article file in present format.
cmd/presentPresent displays slide presentations and articles.
cmd/ssadumpssadump: a tool for displaying and interpreting the SSA form of Go programs.
cmd/stressThe stress utility is intended for catching of episodic failures.
cmd/stringerStringer is a tool to automate the creation of methods that satisfy the fmt.Stringer interface.
cmd/tipCommand tip is the server, serving the latest HEAD straight from the Git oven.
cmd/toolstashToolstash provides a way to save, run, and restore a known good copy of the Go toolchain and to compare the object files generated by two toolchains.
container/intsetsPackage intsets provides Sparse, a compact and fast representation for sparse sets of int values.
coverPackage cover provides support for parsing coverage profiles generated by "go test -coverprofile=cover.out".
go/ast/astutilPackage astutil contains common utilities for working with the Go AST.
go/buildutilPackage buildutil provides utilities related to the go/build package in the standard library.
go/callgraphPackage callgraph defines the call graph and various algorithms and utilities to operate on it.
go/callgraph/chaPackage cha computes the call graph of a Go program using the Class Hierarchy Analysis (CHA) algorithm.
go/callgraph/rtaThis package provides Rapid Type Analysis (RTA) for Go, a fast algorithm for call graph construction and discovery of reachable code (and hence dead code) and runtime types.
go/callgraph/staticPackage static computes the call graph of a Go program containing only static call edges.
godocPackage godoc is a work-in-progress (2013-07-17) package to begin splitting up the godoc binary into multiple pieces.
godoc/analysisPackage analysis performs type and pointer analysis and generates mark-up for the Go source view.
godoc/redirectPackage redirect provides hooks to register HTTP handlers that redirect old godoc paths to their new equivalents and assist in accessing the issue tracker, wiki, code review system, etc.
godoc/staticPackage static exports a map of static file content that supports the godoc user interface.
godoc/utilPackage util contains utility types and functions for godoc.
godoc/vfsPackage vfs defines types for abstract file system access and provides an implementation accessing the file system of the underlying OS.
godoc/vfs/gatefsPackage gatefs provides an implementation of the FileSystem interface that wraps another FileSystem and limits its concurrency.
godoc/vfs/httpfsPackage httpfs implements http.FileSystem using a godoc vfs.FileSystem.
godoc/vfs/mapfsPackage mapfs file provides an implementation of the FileSystem interface based on the contents of a map[string]string.
godoc/vfs/zipfsPackage zipfs file provides an implementation of the FileSystem interface based on the contents of a .zip file.
go/gccgoexportdataPackage gccgoexportdata provides functions for reading export data files containing type information produced by the gccgo compiler.
go/gcexportdataPackage gcexportdata provides functions for locating, reading, and writing export data files containing type information produced by the gc compiler.
go/gcimporter15Package gcimporter15 provides various functions for reading gc-generated object files that can be used to implement the Importer interface defined by the Go 1.5 standard library package.
go/internal/gccgoimporterPackage gccgoimporter implements Import for gccgo-generated object files.
go/loaderPackage loader loads a complete Go program from source code, parsing and type-checking the initial packages plus their transitive closure of dependencies.
go/pointerPackage pointer implements Andersen's analysis, an inclusion-based pointer analysis algorithm first described in (Andersen, 1994).
go/ssaPackage ssa defines a representation of the elements of Go programs (packages, types, functions, variables and constants) using a static single-assignment (SSA) form intermediate representation (IR) for the bodies of functions.
go/ssa/interpPackage ssa/interp defines an interpreter for the SSA representation of Go programs.
go/types/typeutilPackage typeutil defines various utilities for types, such as Map, a mapping from types.Type to interface{} values.
importsPackage imports implements a Go pretty-printer (like package "go/format") that also adds or removes import statements as necessary.
playgroundPackage playground registers HTTP handlers at "/compile" and "/share" that proxy requests to the playground service.
playground/socketPackage socket implements an WebSocket-based playground backend.
presentThe present file format
refactor/egPackage eg implements the example-based refactoring tool whose command-line is defined in
refactor/importgraphPackage importgraph computes the forward and reverse import dependency graphs for all packages in a Go workspace.
refactor/renamePackage rename contains the implementation of the 'gorename' command whose main function is in
refactor/satisfyPackage satisfy inspects the type-checked ASTs of Go packages and reports the set of discovered type constraints of the form (lhs, rhs Type) where lhs is a non-trivial interface, rhs satisfies this interface, and this fact is necessary for the package to be well-typed.

Updated 2017-03-23. Refresh now. Tools for package owners.