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Links2004 Merge pull request #383 from sovcik/master
Implementing automatic WS client-side heartbeat
Latest commit 72731be Jan 16, 2019
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examples added example for heartbeat Oct 24, 2018
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.gitignore first working WebSocketClient May 24, 2015
.travis.yml fix travis debug test build Sep 23, 2018
LICENSE first working WebSocketClient May 24, 2015 bump version to 2.1.0 Feb 7, 2018
library.json version bump Oct 24, 2018 version bump Oct 24, 2018

WebSocket Server and Client for Arduino Build Status

a WebSocket Server and Client for Arduino based on RFC6455.

Supported features of RFC6455
  • text frame
  • binary frame
  • connection close
  • ping
  • pong
  • continuation frame
  • max input length is limited to the ram size and the WEBSOCKETS_MAX_DATA_SIZE define
  • max output length has no limit (the hardware is the limit)
  • Client send big frames with mask 0x00000000 (on AVR all frames)
  • continuation frame reassembly need to be handled in the application code
Limitations for Async
  • Functions called from within the context of the websocket event might not honor yield() and/or delay(). See this issue for more info and a potential workaround.
  • wss / SSL is not possible.
Supported Hardware
  • ESP8266 Arduino for ESP8266
  • ESP32 Arduino for ESP32
  • ESP31B
  • Particle with STM32 ARM Cortex M3
  • ATmega328 with Ethernet Shield (ATmega branch)
  • ATmega328 with enc28j60 (ATmega branch)
  • ATmega2560 with Ethernet Shield (ATmega branch)
  • ATmega2560 with enc28j60 (ATmega branch)

version 2.0 and up is not compatible with AVR/ATmega, check ATmega branch.

Arduino for AVR not supports std namespace of c++.

wss / SSL

supported for:

  • wss client on the ESP8266
  • wss / SSL is not natively supported in WebSocketsServer however it is possible to achieve secure websockets by running the device behind an SSL proxy. See Nginx for a sample Nginx server configuration file to enable this.


This libary can run in Async TCP mode on the ESP.

The mode can be activated in the WebSockets.h (see WEBSOCKETS_NETWORK_TYPE define).

ESPAsyncTCP libary is required.

High Level Client API

  • begin : Initiate connection sequence to the websocket host.
void begin(const char *host, uint16_t port, const char * url = "/", const char * protocol = "arduino");
void begin(String host, uint16_t port, String url = "/", String protocol = "arduino");
  • onEvent: Callback to handle for websocket events
void onEvent(WebSocketClientEvent cbEvent);
  • WebSocketClientEvent: Handler for websocket events
void (*WebSocketClientEvent)(WStype_t type, uint8_t * payload, size_t length)

Where WStype_t type is defined as:

typedef enum {
} WStype_t;


Submit issues to:

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License and credits

The library is licensed under LGPLv2.1

libb64 written by Chris Venter. It is distributed under Public Domain see LICENSE.

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