Overview (Netty API Reference (4.0.56.Final))

Low-level data representation
Package	Description
io.netty.buffer	Abstraction of a byte buffer - the fundamental data structure to represent a low-level binary and text message.

Central interface for all I/O operations
Package	Description
io.netty.channel	The core channel API which is asynchronous and event-driven abstraction of various transports such as a NIO Channel.
io.netty.channel.embedded	A virtual `Channel` that helps wrapping a series of handlers to unit test the handlers or use them in non-I/O context.
io.netty.channel.epoll	Optimized transport for linux which uses EPOLL Edge-Triggered Mode for maximal performance.
io.netty.channel.group	A channel registry which helps a user maintain the list of open `Channel`s and perform bulk operations on them.
io.netty.channel.local	A virtual transport that enables the communication between the two parties in the same virtual machine.
io.netty.channel.nio	NIO-based channel API implementation - recommended for a large number of connections (>= 1000).
io.netty.channel.oio	Old blocking I/O based channel API implementation - recommended for a small number of connections (< 1000).
io.netty.channel.pool	Implementations and API for `Channel` pools.
io.netty.channel.rxtx	A serial and parallel port communication transport based on RXTX.
io.netty.channel.sctp	Abstract SCTP socket interfaces which extend the core channel API.
io.netty.channel.sctp.nio	NIO-based SCTP Channel API implementation - recommended for a large number of connections (>= 1000).
io.netty.channel.sctp.oio	Old blocking I/O based SCTP channel API implementation - recommended for a small number of connections (< 1000).
io.netty.channel.socket	Abstract TCP and UDP socket interfaces which extend the core channel API.
io.netty.channel.socket.nio	NIO-based socket channel API implementation - recommended for a large number of connections (>= 1000).
io.netty.channel.socket.oio	Old blocking I/O based socket channel API implementation - recommended for a small number of connections (< 1000).
io.netty.channel.udt	UDT Transport.
io.netty.channel.udt.nio	UDT Transport for NIO Channels.
io.netty.channel.unix	Unix specific transport.

Client & Server bootstrapping utilities
Package	Description
io.netty.bootstrap	The helper classes with fluent API which enable an easy implementation of typical client side and server side channel initialization.

Reusable I/O event interceptors
Package	Description
io.netty.handler.codec	Extensible decoder and its common implementations which deal with the packet fragmentation and reassembly issue found in a stream-based transport such as TCP/IP.
io.netty.handler.codec.base64	Encoder and decoder which transform a Base64-encoded `String` or `ByteBuf` into a decoded `ByteBuf` and vice versa.
io.netty.handler.codec.bytes	Encoder and decoder which transform an array of bytes into a `ByteBuf` and vice versa.
io.netty.handler.codec.compression	Encoder and decoder which compresses and decompresses `ByteBuf`s in a compression format such as zlib, gzip, and Snappy.
io.netty.handler.codec.haproxy	Decodes an HAProxy proxy protocol header
io.netty.handler.codec.http	Encoder, decoder and their related message types for HTTP.
io.netty.handler.codec.http.cookie	This package contains Cookie related classes.
io.netty.handler.codec.http.cors	This package contains Cross Origin Resource Sharing (CORS) related classes.
io.netty.handler.codec.http.multipart	HTTP multipart support.
io.netty.handler.codec.http.websocketx	Encoder, decoder, handshakers and their related message types for Web Socket data frames.
io.netty.handler.codec.marshalling	Decoder and Encoder which uses JBoss Marshalling.
io.netty.handler.codec.protobuf	Encoder and decoder which transform a Google Protocol Buffers `Message` into a `ByteBuf` and vice versa.
io.netty.handler.codec.rtsp	An RTSP extension based on the HTTP codec.
io.netty.handler.codec.sctp	Decoder and encoders to manage message completion and multi-streaming codec in SCTP/IP.
io.netty.handler.codec.serialization	Encoder, decoder and their compatibility stream implementations which transform a `Serializable` object into a byte buffer and vice versa.
io.netty.handler.codec.socks	Encoder, decoder and their related message types for Socks.
io.netty.handler.codec.spdy	Encoder, decoder, session handler and their related message types for the SPDY protocol.
io.netty.handler.codec.string	Encoder and decoder which transform a `String` into a `ByteBuf` and vice versa.
io.netty.handler.flush	Package to control flush behavior.
io.netty.handler.ipfilter	Package to filter IP addresses (allow/deny).
io.netty.handler.logging	Logs a `io.netty.channel.ChannelEvent` for debugging purpose.
io.netty.handler.ssl	SSL · TLS implementation based on `SSLEngine`
io.netty.handler.ssl.ocsp	OCSP stapling, formally known as the TLS Certificate Status Request extension, is an alternative approach to the Online Certificate Status Protocol (OCSP) for checking the revocation status of X.509 digital certificates.
io.netty.handler.ssl.util	Utility classes that helps easier development of TLS/SSL applications.
io.netty.handler.stream	Writes very large data stream asynchronously neither spending a lot of memory nor getting `OutOfMemoryError`.
io.netty.handler.timeout	Adds support for read and write timeout and idle connection notification using a `Timer`.
io.netty.handler.traffic	Implementation of a Traffic Shaping Handler and Dynamic Statistics.

Miscellaneous
Package	Description
io.netty.util	Utility classes used across multiple packages.
io.netty.util.collection	Utility classes for commonly used collections.
io.netty.util.concurrent	Utility classes for concurrent / async tasks.