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Packages

Standard library ▾

Name Synopsis
archive
tar Package tar implements access to tar archives.
zip Package zip provides support for reading and writing ZIP archives.
arena The arena package provides the ability to allocate memory for a collection of Go values and free that space manually all at once, safely.
bufio Package bufio implements buffered I/O. It wraps an io.Reader or io.Writer object, creating another object (Reader or Writer) 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.
bytes Package bytes implements functions for the manipulation of byte slices.
cmp Package cmp provides types and functions related to comparing ordered values.
compress
bzip2 Package bzip2 implements bzip2 decompression.
flate Package flate implements the DEFLATE compressed data format, described in RFC 1951.
gzip Package gzip implements reading and writing of gzip format compressed files, as specified in RFC 1952.
lzw 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) (June 1984), pp 8-19.
zlib Package zlib implements reading and writing of zlib format compressed data, as specified in RFC 1950.
container
heap Package heap provides heap operations for any type that implements heap.Interface.
list Package list implements a doubly linked list.
ring Package ring implements operations on circular lists.
context Package context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
crypto Package crypto collects common cryptographic constants.
aes Package aes implements AES encryption (formerly Rijndael), as defined in U.S. Federal Information Processing Standards Publication 197.
boring Package boring exposes functions that are only available when building with Go+BoringCrypto.
cipher Package cipher implements standard block cipher modes that can be wrapped around low-level block cipher implementations.
des Package des implements the Data Encryption Standard (DES) and the Triple Data Encryption Algorithm (TDEA) as defined in U.S. Federal Information Processing Standards Publication 46-3.
dsa Package dsa implements the Digital Signature Algorithm, as defined in FIPS 186-3.
ecdh Package ecdh implements Elliptic Curve Diffie-Hellman over NIST curves and Curve25519.
ecdsa Package ecdsa implements the Elliptic Curve Digital Signature Algorithm, as defined in FIPS 186-4 and SEC 1, Version 2.0.
ed25519 Package ed25519 implements the Ed25519 signature algorithm.
elliptic Package elliptic implements the standard NIST P-224, P-256, P-384, and P-521 elliptic curves over prime fields.
hmac Package hmac implements the Keyed-Hash Message Authentication Code (HMAC) as defined in U.S. Federal Information Processing Standards Publication 198.
md5 Package md5 implements the MD5 hash algorithm as defined in RFC 1321.
rand Package rand implements a cryptographically secure random number generator.
rc4 Package rc4 implements RC4 encryption, as defined in Bruce Schneier's Applied Cryptography.
rsa Package rsa implements RSA encryption as specified in PKCS #1 and RFC 8017.
sha1 Package sha1 implements the SHA-1 hash algorithm as defined in RFC 3174.
sha256 Package sha256 implements the SHA224 and SHA256 hash algorithms as defined in FIPS 180-4.
sha512 Package sha512 implements the SHA-384, SHA-512, SHA-512/224, and SHA-512/256 hash algorithms as defined in FIPS 180-4.
subtle Package subtle implements functions that are often useful in cryptographic code but require careful thought to use correctly.
tls Package tls partially implements TLS 1.2, as specified in RFC 5246, and TLS 1.3, as specified in RFC 8446.
fipsonly Package fipsonly restricts all TLS configuration to FIPS-approved settings.
x509 Package x509 implements a subset of the X.509 standard.
pkix 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) databases.
driver Package driver defines interfaces to be implemented by database drivers as used by package sql.
debug
buildinfo Package buildinfo provides access to information embedded in a Go binary about how it was built.
dwarf Package dwarf provides access to DWARF debugging information loaded from executable files, as defined in the DWARF 2.0 Standard at http://dwarfstd.org/doc/dwarf-2.0.0.pdf.
elf Package elf implements access to ELF object files.
gosym Package gosym implements access to the Go symbol and line number tables embedded in Go binaries generated by the gc compilers.
macho Package macho implements access to Mach-O object files.
pe Package pe implements access to PE (Microsoft Windows Portable Executable) files.
plan9obj Package plan9obj implements access to Plan 9 a.out object files.
embed Package embed provides access to files embedded in the running Go program.
encoding Package encoding defines interfaces shared by other packages that convert data to and from byte-level and textual representations.
ascii85 Package ascii85 implements the ascii85 data encoding as used in the btoa tool and Adobe's PostScript and PDF document formats.
asn1 Package asn1 implements parsing of DER-encoded ASN.1 data structures, as defined in ITU-T Rec X.690.
base32 Package base32 implements base32 encoding as specified by RFC 4648.
base64 Package base64 implements base64 encoding as specified by RFC 4648.
binary Package binary implements simple translation between numbers and byte sequences and encoding and decoding of varints.
csv Package csv reads and writes comma-separated values (CSV) files.
gob Package gob manages streams of gobs - binary values exchanged between an [Encoder] (transmitter) and a [Decoder] (receiver).
hex Package hex implements hexadecimal encoding and decoding.
json Package json implements encoding and decoding of JSON as defined in RFC 7159.
pem Package pem implements the PEM data encoding, which originated in Privacy Enhanced Mail.
xml Package xml implements a simple XML 1.0 parser that understands XML name spaces.
errors Package errors implements functions to manipulate errors.
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
ast Package ast declares the types used to represent syntax trees for Go packages.
build Package build gathers information about Go packages.
constraint Package constraint implements parsing and evaluation of build constraint lines.
constant Package constant implements Values representing untyped Go constants and their corresponding operations.
doc Package doc extracts source code documentation from a Go AST.
comment Package comment implements parsing and reformatting of Go doc comments, (documentation comments), which are comments that immediately precede a top-level declaration of a package, const, func, type, or var.
format Package format implements standard formatting of Go source.
importer Package importer provides access to export data importers.
parser Package parser implements a parser for Go source files.
printer Package printer implements printing of AST nodes.
scanner Package scanner implements a scanner for Go source text.
token Package token defines constants representing the lexical tokens of the Go programming language and basic operations on tokens (printing, predicates).
types Package types declares the data types and implements the algorithms for type-checking of Go packages.
version Package version provides operations on [Go versions] in [Go toolchain name syntax]: strings like "go1.20", "go1.21.0", "go1.22rc2", and "go1.23.4-bigcorp".
hash Package hash provides interfaces for hash functions.
adler32 Package adler32 implements the Adler-32 checksum.
crc32 Package crc32 implements the 32-bit cyclic redundancy check, or CRC-32, checksum.
crc64 Package crc64 implements the 64-bit cyclic redundancy check, or CRC-64, checksum.
fnv Package fnv implements FNV-1 and FNV-1a, non-cryptographic hash functions created by Glenn Fowler, Landon Curt Noll, and Phong Vo.
maphash Package maphash provides hash functions on byte sequences.
html Package html provides functions for escaping and unescaping HTML text.
template Package template (html/template) implements data-driven templates for generating HTML output safe against code injection.
image Package image implements a basic 2-D image library.
color Package color implements a basic color library.
palette Package palette provides standard color palettes.
draw Package draw provides image composition functions.
gif Package gif implements a GIF image decoder and encoder.
jpeg Package jpeg implements a JPEG image decoder and encoder.
png Package png implements a PNG image decoder and encoder.
index
suffixarray Package suffixarray implements substring search in logarithmic time using an in-memory suffix array.
io Package io provides basic interfaces to I/O primitives.
fs Package fs defines basic interfaces to a file system.
ioutil Package ioutil implements some I/O utility functions.
iter Package iter provides basic definitions and operations related to iterators over sequences.
log Package log implements a simple logging package.
slog Package slog provides structured logging, in which log records include a message, a severity level, and various other attributes expressed as key-value pairs.
syslog Package syslog provides a simple interface to the system log service.
maps Package maps defines various functions useful with maps of any type.
math Package math provides basic constants and mathematical functions.
big Package big implements arbitrary-precision arithmetic (big numbers).
bits Package bits implements bit counting and manipulation functions for the predeclared unsigned integer types.
cmplx Package cmplx provides basic constants and mathematical functions for complex numbers.
rand Package rand implements pseudo-random number generators suitable for tasks such as simulation, but it should not be used for security-sensitive work.
v2 Package rand implements pseudo-random number generators suitable for tasks such as simulation, but it should not be used for security-sensitive work.
mime Package mime implements parts of the MIME spec.
multipart Package multipart implements MIME multipart parsing, as defined in RFC 2046.
quotedprintable Package quotedprintable implements quoted-printable encoding as specified by RFC 2045.
net Package net provides a portable interface for network I/O, including TCP/IP, UDP, domain name resolution, and Unix domain sockets.
http Package http provides HTTP client and server implementations.
cgi Package cgi implements CGI (Common Gateway Interface) as specified in RFC 3875.
cookiejar Package cookiejar implements an in-memory RFC 6265-compliant http.CookieJar.
fcgi Package fcgi implements the FastCGI protocol.
httptest Package httptest provides utilities for HTTP testing.
httptrace Package httptrace provides mechanisms to trace the events within HTTP client requests.
httputil Package httputil provides HTTP utility functions, complementing the more common ones in the net/http package.
pprof Package pprof serves via its HTTP server runtime profiling data in the format expected by the pprof visualization tool.
mail Package mail implements parsing of mail messages.
netip Package netip defines an IP address type that's a small value type.
rpc Package rpc provides access to the exported methods of an object across a network or other I/O connection.
jsonrpc Package jsonrpc implements a JSON-RPC 1.0 ClientCodec and ServerCodec for the rpc package.
smtp Package smtp implements the Simple Mail Transfer Protocol as defined in RFC 5321.
textproto Package textproto implements generic support for text-based request/response protocols in the style of HTTP, NNTP, and SMTP.
url Package url parses URLs and implements query escaping.
os Package os provides a platform-independent interface to operating system functionality.
exec Package exec runs external commands.
signal Package signal implements access to incoming signals.
user Package user allows user account lookups by name or id.
path Package path implements utility routines for manipulating slash-separated paths.
filepath 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.
reflect Package reflect implements run-time reflection, allowing a program to manipulate objects with arbitrary types.
regexp Package regexp implements regular expression search.
syntax 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.
asan
cgo Package cgo contains runtime support for code generated by the cgo tool.
coverage
debug Package debug contains facilities for programs to debug themselves while they are running.
metrics Package metrics provides a stable interface to access implementation-defined metrics exported by the Go runtime.
msan
pprof Package pprof writes runtime profiling data in the format expected by the pprof visualization tool.
race Package race implements data race detection logic.
trace Package trace contains facilities for programs to generate traces for the Go execution tracer.
slices Package slices defines various functions useful with slices of any type.
sort Package sort provides primitives for sorting slices and user-defined collections.
strconv 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.
structs Package structs defines marker types that can be used as struct fields to modify the properties of a struct.
sync Package sync provides basic synchronization primitives such as mutual exclusion locks.
atomic Package atomic provides low-level atomic memory primitives useful for implementing synchronization algorithms.
syscall Package syscall contains an interface to the low-level operating system primitives.
js Package js gives access to the WebAssembly host environment when using the js/wasm architecture.
testing Package testing provides support for automated testing of Go packages.
fstest Package fstest implements support for testing implementations and users of file systems.
iotest Package iotest implements Readers and Writers useful mainly for testing.
quick Package quick implements utility functions to help with black box testing.
slogtest Package slogtest implements support for testing implementations of log/slog.Handler.
text
scanner Package scanner provides a scanner and tokenizer for UTF-8-encoded text.
tabwriter Package tabwriter implements a write filter (tabwriter.Writer) that translates tabbed columns in input into properly aligned text.
template Package template implements data-driven templates for generating textual output.
parse Package parse builds parse trees for templates as defined by text/template and html/template.
time Package time provides functionality for measuring and displaying time.
tzdata Package tzdata provides an embedded copy of the timezone database.
unicode Package unicode provides data and functions to test some properties of Unicode code points.
utf16 Package utf16 implements encoding and decoding of UTF-16 sequences.
utf8 Package utf8 implements functions and constants to support text encoded in UTF-8.
unique The unique package provides facilities for canonicalizing ("interning") comparable values.
unsafe Package unsafe contains operations that step around the type safety of Go programs.

Other packages

Sub-repositories

These packages are part of the Go Project but outside the main Go tree. They are developed under looser compatibility requirements than the Go core. Install them with "go get".

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