• Package tar implements access to tar archives.
• archive/zip Package zip provides support for reading and writing ZIP archives.
• Package bufio implements buffered I/O. It wraps an io.Reader or io.Writer object, creating another object (Reader or Writer.md) that also implements the interface but provides buffering and some help for textual I/O.
• builtin Package builtin provides documentation for Go’s predeclared identifiers.
• Package bytes implements functions for the manipulation of byte slices.
• compress/bzip2 Package bzip2 implements bzip2 decompression.
• Package flate implements the DEFLATE compressed data format, described in RFC 1951.
• compress/gzip Package gzip implements reading and writing of gzip format compressed files, as specified in RFC 1952.
• Package lzw implements the Lempel-Ziv-Welch compressed data format, described in T. A. Welch, ``A Technique for High-Performance Data Compression’’, Computer, 17(6.md) (June 1984.md), pp 8-19.
• compress/zlib Package zlib implements reading and writing of zlib format compressed data, as specified in RFC 1950.
• Package heap provides heap operations for any type that implements heap.Interface.
• container/list Package list implements a doubly linked list.
• Package ring implements operations on circular lists.
• context Package context defines the Context type, which carries deadlines, cancelation signals, and other request-scoped values across API boundaries and between processes.
• Package crypto collects common cryptographic constants.
• crypto/aes Package aes implements AES encryption (formerly Rijndael.md), as defined in U.S. Federal Information Processing Standards Publication 197.
• Package cipher implements standard block cipher modes that can be wrapped around low-level block cipher implementations.
• crypto/des Package des implements the Data Encryption Standard (DES.md) and the Triple Data Encryption Algorithm (TDEA.md) as defined in U.S. Federal Information Processing Standards Publication 46-3.
• Package dsa implements the Digital Signature Algorithm, as defined in FIPS 186-3.
• crypto/ecdsa Package ecdsa implements the Elliptic Curve Digital Signature Algorithm, as defined in FIPS 186-3.
• Package elliptic implements several standard elliptic curves over prime fields.
• crypto/hmac Package hmac implements the Keyed-Hash Message Authentication Code (HMAC.md) as defined in U.S. Federal Information Processing Standards Publication 198.
• Package md5 implements the MD5 hash algorithm as defined in RFC 1321.
• crypto/rand Package rand implements a cryptographically secure pseudorandom number generator.
• Package rc4 implements RC4 encryption, as defined in Bruce Schneier’s Applied Cryptography.
• crypto/rsa Package rsa implements RSA encryption as specified in PKCS#1.
• Package sha1 implements the SHA-1 hash algorithm as defined in RFC 3174.
• crypto/sha256 Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4.
• Package sha512 implements the SHA-384, SHA-512, SHA-512/224, and SHA-512/256 hash algorithms as defined in FIPS 180-4.
• crypto/subtle Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly.
• Package tls partially implements TLS 1.2, as specified in RFC 5246.
• crypto/x509 Package x509 parses X.509-encoded keys and certificates.
• Package pkix contains shared, low level structures used for ASN.1 parsing and serialization of X.509 certificates, CRL and OCSP.
• database/sql Package sql provides a generic interface around SQL (or SQL-like.md) databases.
• Package driver defines interfaces to be implemented by database drivers as used by package sql.
• debug/dwarf Package dwarf provides access to DWARF debugging information loaded from executable files, as defined in the DWARF 2.0 Standard at
• debug/elf Package elf implements access to ELF object files.
• Package gosym implements access to the Go symbol and line number tables embedded in Go binaries generated by the gc compilers.
• debug/macho Package macho implements access to Mach-O object files.
• Package pe implements access to PE (Microsoft Windows Portable Executable.md) files.
• debug/plan9obj Package plan9obj implements access to Plan 9 a.out object files.
• Package encoding defines interfaces shared by other packages that convert data to and from byte-level and textual representations.
• encoding/ascii85 Package ascii85 implements the ascii85 data encoding as used in the btoa tool and Adobe’s PostScript and PDF document formats.
• Package asn1 implements parsing of DER-encoded ASN.1 data structures, as defined in ITU-T Rec X.690.
• encoding/base32 Package base32 implements base32 encoding as specified by RFC 4648.
• Package base64 implements base64 encoding as specified by RFC 4648.
• encoding/binary Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints.
• Package gob manages streams of gobs - binary values exchanged between an Encoder (transmitter.md) and a Decoder (receiver.md).
• encoding/hex Package hex implements hexadecimal encoding and decoding.
• Package json implements encoding and decoding of JSON as defined in RFC 7159.
• encoding/pem Package pem implements the PEM data encoding, which originated in Privacy Enhanced Mail.
• Package xml implements a simple XML 1.0 parser that understands XML name spaces.
• errors Package errors implements functions to manipulate errors.
• Package expvar provides a standardized interface to public variables, such as operation counters in servers.
• flag Package flag implements command-line flag parsing.
• Package fmt implements formatted I/O with functions analogous to C’s printf and scanf.
• go/ast Package ast declares the types used to represent syntax trees for Go packages.
• Package build gathers information about Go packages.
• go/constant Package constant implements Values representing untyped Go constants and their corresponding operations.
• Package doc extracts source code documentation from a Go AST.
• go/format Package format implements standard formatting of Go source.
• Package importer provides access to export data importers.
• go/parser Package parser implements a parser for Go source files.
• Package printer implements printing of AST nodes.
• go/scanner Package scanner implements a scanner for Go source text.
• Package token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates.md).
• go/types Package types declares the data types and implements the algorithms for type-checking of Go packages.
• Package hash provides interfaces for hash functions.
• hash/adler32 Package adler32 implements the Adler-32 checksum.
• Package crc32 implements the 32-bit cyclic redundancy check, or CRC-32, checksum.
• hash/crc64 Package crc64 implements the 64-bit cyclic redundancy check, or CRC-64, checksum.
• Package fnv implements FNV-1 and FNV-1a, non-cryptographic hash functions created by Glenn Fowler, Landon Curt Noll, and Phong Vo.
• html Package html provides functions for escaping and unescaping HTML text.
• Package template (html/template.md) implements data-driven templates for generating HTML output safe against code injection.
• image Package image implements a basic 2-D image library.
• Package color implements a basic color library.
• image/color/palette Package palette provides standard color palettes.
• Package draw provides image composition functions.
• image/gif Package gif implements a GIF image decoder and encoder.
• Package jpeg implements a JPEG image decoder and encoder.
• image/png Package png implements a PNG image decoder and encoder.
• Package suffixarray implements substring search in logarithmic time using an in-memory suffix array.
• io Package io provides basic interfaces to I/O primitives.
• Package ioutil implements some I/O utility functions.
• log Package log implements a simple logging package.
• Package syslog provides a simple interface to the system log service.
• math Package math provides basic constants and mathematical functions.
• Package big implements arbitrary-precision arithmetic (big numbers.md).
• math/bits Package bits implements bit counting and manipulation functions for the predeclared unsigned integer types.
• Package cmplx provides basic constants and mathematical functions for complex numbers.
• math/rand Package rand implements pseudo-random number generators.
• Package mime implements parts of the MIME spec.
• mime/multipart Package multipart implements MIME multipart parsing, as defined in RFC 2046.
• Package quotedprintable implements quoted-printable encoding as specified by RFC 2045.
• net/http Package http provides HTTP client and server implementations.
• Package cgi implements CGI (Common Gateway Interface.md) as specified in RFC 3875.
• net/http/cookiejar Package cookiejar implements an in-memory RFC 6265-compliant http.CookieJar.
• Package fcgi implements the FastCGI protocol.
• net/http/httptest Package httptest provides utilities for HTTP testing.
• Package httptrace provides mechanisms to trace the events within HTTP client requests.
• net/http/httputil Package httputil provides HTTP utility functions, complementing the more common ones in the net/http package.
• Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool.
• net/mail Package mail implements parsing of mail messages.
• Package rpc provides access to the exported methods of an object across a network or other I/O connection.
• net/rpc/jsonrpc Package jsonrpc implements a JSON-RPC 1.0 ClientCodec and ServerCodec for the rpc package.
• Package smtp implements the Simple Mail Transfer Protocol as defined in RFC 5321.
• net/textproto Package textproto implements generic support for text-based request/response protocols in the style of HTTP, NNTP, and SMTP.
• Package url parses URLs and implements query escaping.
• os Package os provides a platform-independent interface to operating system functionality.
• Package exec runs external commands.
• os/signal Package signal implements access to incoming signals.
• Package user allows user account lookups by name or id.
• path Package path implements utility routines for manipulating slash-separated paths.
• Package filepath implements utility routines for manipulating filename paths in a way compatible with the target operating system-defined file paths.
• plugin Package plugin implements loading and symbol resolution of Go plugins.
• Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types.
• regexp Package regexp implements regular expression search.
• Package syntax parses regular expressions into parse trees and compiles parse trees into programs.
• runtime Package runtime contains operations that interact with Go’s runtime system, such as functions to control goroutines.
• Package cgo contains runtime support for code generated by the cgo tool.
• runtime/debug Package debug contains facilities for programs to debug themselves while they are running.
• Package pprof writes runtime profiling data in the format expected by the pprof visualization tool.
• runtime/race Package race implements data race detection logic.
• Package trace contains facilities for programs to generate trace for Go execution tracer.
• sort Package sort provides primitives for sorting slices and user-defined collections.
• 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.
• Package sync provides basic synchronization primitives such as mutual exclusion locks.
• sync/atomic Package atomic provides low-level atomic memory primitives useful for implementing synchronization algorithms.
• Package syscall contains an interface to the low-level operating system primitives.
• testing Package testing provides support for automated testing of Go packages.
• Package iotest implements Readers and Writers useful mainly for testing.
• testing/quick Package quick implements utility functions to help with black box testing.
• Package scanner provides a scanner and tokenizer for UTF-8-encoded text.
• text/tabwriter Package tabwriter implements a write filter (tabwriter.Writer.md) that translates tabbed columns in input into properly aligned text.
• Package template implements data-driven templates for generating textual output.
• text/template/parse Package parse builds parse trees for templates as defined by text/template and html/template.
• Package time provides functionality for measuring and displaying time.
• unicode Package unicode provides data and functions to test some properties of Unicode code points.
• Package utf16 implements encoding and decoding of UTF-16 sequences.
• unicode/utf8 Package utf8 implements functions and constants to support text encoded in UTF-8.