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Arduino core for ESP8266 WiFi chip

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Arduino on ESP8266

This project brings support for the ESP8266 chip to the Arduino environment. It lets you write sketches, using familiar Arduino functions and libraries, and run them directly on ESP8266, with no external microcontroller required.

ESP8266 Arduino core comes with libraries to communicate over WiFi using TCP and UDP, set up HTTP, mDNS, SSDP, and DNS servers, do OTA updates, use a file system in flash memory, and work with SD cards, servos, SPI and I2C peripherals.


Installing with Boards Manager

Starting with 1.6.4, Arduino allows installation of third-party platform packages using Boards Manager. We have packages available for Windows, Mac OS, and Linux (32 and 64 bit).

  • Download and install Arduino IDE 1.x or 2.x
  • Start Arduino and open the Preferences window
  • Enter into the File>Preferences>Additional Boards Manager URLs field of the Arduino IDE. You can add multiple URLs, separating them with commas.
  • Open Boards Manager from Tools > Board menu and install esp8266 platform (and don't forget to select your ESP8266 board from Tools > Board menu after installation).

Latest release Latest release

Boards manager link:


Using git version

Also known as latest git or master branch.

Using PlatformIO

PlatformIO is an open source ecosystem for IoT development with a cross-platform build system, a library manager, and full support for Espressif (ESP8266) development. It works on the following popular host operating systems: macOS, Windows, Linux 32/64, and Linux ARM (like Raspberry Pi, BeagleBone, CubieBoard).

Building with make

makeEspArduino is a generic makefile for any ESP8266 Arduino project. Using make instead of the Arduino IDE makes it easier to do automated and production builds.


Documentation for latest development version:

Issues and support

ESP8266 Community Forum is a well-established community for questions and answers about Arduino for ESP8266. Stackoverflow is also an alternative. If you need help, have a "How do I..." type question, have a problem with a 3rd party library not hosted in this repo, or just want to discuss how to approach a problem, please ask there.

If you find the forum useful, please consider supporting it with a donation.

If you encounter an issue which you think is a bug in the ESP8266 Arduino Core or the associated libraries, or if you want to propose an enhancement, you are welcome to submit it here on Github:

Please provide as much context as possible, as well as the information requested in the issue template:

  • ESP8266 Arduino core version which you are using (you can check it in Boards Manager)
  • your sketch code; please wrap it into a code block, see Github markdown manual
  • when encountering an issue that happens at run time, attach the serial output. Wrap it into a code block, just like the code.
  • for issues that happen at compile time, enable verbose compiler output in the IDE preferences, and attach that output (also inside a code block)
  • ESP8266 development board model
  • IDE settings (board choice, flash size)
  • etc


For minor fixes of code and documentation, please go ahead and submit a pull request. A gentle introduction to the process can be found here.

Check out the list of issues that are easy to fix — easy issues pending. Working on them is a great way to move the project forward.

Larger changes (rewriting parts of existing code from scratch, adding new functions to the core, adding new libraries) should generally be discussed by opening an issue first. PRs with such changes require testing and approval.

Feature branches with lots of small commits (especially titled "oops", "fix typo", "forgot to add file", etc.) should be squashed before opening a pull request. At the same time, please refrain from putting multiple unrelated changes into a single pull request.

License and credits

Arduino IDE is developed and maintained by the Arduino team. The IDE is licensed under GPL.

ESP8266 core includes an xtensa gcc toolchain, which is also under GPL. was initially created by Fredrik Ahlberg (@themadinventor, @kongo), and is currently maintained by Angus Gratton (@projectgus) under GPL 2.0 license.

Espressif's NONOS SDK included in this build is under Espressif MIT License.

ESP8266 core files are licensed under LGPL.

SPI Flash File System (SPIFFS) written by Peter Andersson is used in this project. It is distributed under the MIT license.

umm_malloc memory management library written by Ralph Hempel is used in this project. It is distributed under the MIT license.

SoftwareSerial library and examples written by Peter Lerup. Distributed under LGPL 2.1.

BearSSL library written by Thomas Pornin, built from, is used in this project. It is distributed under the MIT License.

LittleFS library written by ARM Limited and released under the BSD 3-clause license.

uzlib library written and (c) 2014-2018 Paul Sokolovsky, licensed under the ZLib license ( uzlib is based on: tinf library by Joergen Ibsen (Deflate decompression); Deflate Static Huffman tree routines by Simon Tatham; LZ77 compressor by Paul Sokolovsky; with library integrated and maintained by Paul Sokolovsky.

Other useful links

Toolchain repo

Lwip link layer repo

SoftwareSerial repo

Serial Monitor Arduino IDE plugin Original discussion here, quick download there.

FTP Client/Server Library