Installing

Boards Manager

This is the suggested installation method for end users.

Prerequisites

Internet connection
Arduino IDE 1.x or 2.x (https://www.arduino.cc/en/software)
(macOS/Linux only) Python ≥3.7 (https://python.org)

Instructions

Start Arduino and open Preferences window.
Enter https://arduino.esp8266.com/stable/package_esp8266com_index.json into Additional Board Manager URLs field. You can add multiple URLs, separating them with commas.
Open Boards Manager from Tools > Board menu and find esp8266 platform.
Select the version you need from a drop-down box.
Click install button.
Don't forget to select your ESP8266 board from Tools > Board menu after installation.

For more information on the Arduino Board Manager, see:

https://www.arduino.cc/en/guide/cores

Using git version

This is the suggested installation method for contributors and library developers.

Prerequisites

Internet connection
Arduino IDE 1.x or 2.x (https://www.arduino.cc/en/software)
git (https://git-scm.com)
Python ≥3.7 (https://python.org)
terminal, console, or command prompt (depending on your OS)
Uninstalling any core version installed via Board Manager

Instructions - Windows 10

First, make sure you don't already have an ESP8266 core version installed using the Board Manager (see above). If you do, uninstall it from the Board Manager before proceeding. It is also advisable to erase the Arduino15 contents.
Install git for Windows (if not already; see https://git-scm.com/download/win)
Open a command prompt (cmd) and go to Arduino default directory. This is typically the sketchbook directory (usually C:\Users\{username}\Documents\Arduino where the environment variable %USERPROFILE% usually contains C:\Users\{username})

Clone this repository into hardware/esp8266com/esp8266 directory.

cd %USERPROFILE%\Documents\Arduino\
if not exist hardware mkdir hardware
cd hardware
if not exist esp8266com mkdir esp8266com
cd esp8266com
git clone https://github.com/esp8266/Arduino.git esp8266

You should end up with the following directory structure in

C:\Users\{your username}\Documents\

Arduino
|
--- libraries
--- hardware
    |
    --- esp8266com
        |
        --- esp8266
            |
            --- bootloaders
            --- cores
            --- doc
            --- libraries
            --- package
            --- tests
            --- tools
            --- variants
            --- platform.txt
            --- programmers.txt
            --- README.md
            --- boards.txt
            --- LICENSE

Initialize submodules to fetch external libraries

cd %USERPROFILE%\Documents\Arduino\hardware\esp8266com\esp8266
git submodule update --init

Not doing this step would cause build failure when attempting to include SoftwareSerial.h, Ethernet.h, etc. See our .gitmodules file for the full list.

Download binary tools
```
cd tools
python3 get.py
```
Restart Arduino
If using the Arduino IDE for Visual Studio (https://www.visualmicro.com/), be sure to click Tools - Visual Micro - Rescan Toolchains and Libraries
When later updating your local library, goto the esp8266 directory and do a git pull
```
cd %USERPROFILE%\Documents\Arduino\hardware\esp8266com\esp8266
git status
git pull
```

Note that you could, in theory install in C:\Program Files (x86)\Arduino\hardware however this has security implications, not to mention the directory often gets blown away when re-installing Arduino IDE. It does have the benefit (or drawback, depending on your perspective) - of being available to all users on your PC that use Arduino.

Instructions - Other OS

First, make sure you don't already have an ESP8266 core version installed using the Board Manager (see above). If you do, uninstall it from the Board Manager before proceeding. It is also advisable to erase the .arduino15 (Linux) or Arduino15 (MacOS) contents.
Open the console and go to Arduino directory. This can be either your sketchbook directory (usually <Documents>/Arduino), or the directory of Arduino application itself, the choice is up to you.

Clone this repository into hardware/esp8266com/esp8266 directory. Alternatively, clone it elsewhere and create a symlink, if your OS supports them.

cd hardware
mkdir esp8266com
cd esp8266com
git clone https://github.com/esp8266/Arduino.git esp8266

You should end up with the following directory structure:

Arduino
|
--- hardware
    |
    --- esp8266com
        |
        --- esp8266
            |
            --- bootloaders
            --- cores
            --- doc
            --- libraries
            --- package
            --- tests
            --- tools
            --- variants
            --- platform.txt
            --- programmers.txt
            --- README.md
            --- boards.txt
            --- LICENSE

Initialize submodules to fetch external libraries
```
cd esp8266
git submodule update --init
```

Not doing this step would cause build failure when attempting to include SoftwareSerial.h, Ethernet.h, etc. See our .gitmodules file for the full list.

Download binary tools
```
cd tools
python3 get.py
```

If you get an error message stating that python3 is not found, you will need to install it (most modern UNIX-like OSes provide Python 3 as part of the default install). To install you will need to use sudo yum install python3, sudo apt install python3, or brew install python3 as appropriate. On the Mac you may get an error message like:
python3 get.py
Platform: x86_64-apple-darwin
Downloading python3-macosx-placeholder.tar.gz
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/urllib/request.py", line 1317, in do_open
    encode_chunked=req.has_header('Transfer-encoding'))
  ...
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/ssl.py", line 1117, in do_handshake
    self._sslobj.do_handshake()
ssl.SSLCertVerificationError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1056)
This is because Homebrew on the Mac does not always install the required SSL certificates by default. Install them manually (adjust the Python 3.7 as needed) with:
cd "/Applications/Python 3.7/" && sudo "./Install Certificates.command"

Restart Arduino
When later updating your local library, goto the esp8266 directory and do a git pull
```
cd hardware\esp8266com\esp8266
git status
git pull
```

Maintaining

To keep up with the development branch

git switch --recurse-submodules --discard-changes master
git pull --recurse-submodules
cd tools
python3 get.py

Pull requests

To test not yet merged Pull Request, first you have to find its ID number. This is the sequence of digits right after the pull request title.

Open terminal and cd into the directory where the repository was previously cloned. For example, 12345 is the Pull Request ID

git fetch origin pull/12345/head
git switch --detach --recurse-submodules --discard-changes FETCH_HEAD

When Pull Request updates packaged tools, make sure to also fetch their latest versions.

cd tools
python3 get.py

To go back to using the development branch

git switch --recurse-submodules --discard-changes master
git pull --recurse-submodules

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).

What is PlatformIO?
PlatformIO IDE
PlatformIO Core (command line tool)
Advanced usage - custom settings, uploading to LittleFS, Over-the-Air (OTA), staging version
Using Arduino Framework Staging Version - install development version of the Core
Integration with Cloud and Standalone IDEs - Cloud9, Codeanywhere, Eclipse Che (Codenvy), Atom, CLion, Eclipse, Emacs, NetBeans, Qt Creator, Sublime Text, VIM, Visual Studio, and VSCode
Project Examples