There are essentially three ways to build your NodeMCU firmware: cloud build service, Docker image, dedicated Linux environment (possibly VM).


Cloud Build Service

NodeMCU "application developers" just need a ready-made firmware. There's a cloud build service with a nice UI and configuration options for them.

Docker Image

Occasional NodeMCU firmware hackers don't need full control over the complete tool chain. They might not want to setup a Linux VM with the build environment. Docker to the rescue. Give Docker NodeMCU build a try.

Linux Build Environment

NodeMCU firmware developers commit or contribute to the project on GitHub and might want to build their own full fledged build environment with the complete tool chain. The NodeMCU project embeds a ready-made tool chain for Linux/x86-64 by default. After working through the Build Options below, simply start the build process with


The default build setup reduces output verbosity to a minimum. The verbosity level can be increased by setting the V environment variable to 1, as below. See the root Makefile for other available options.

V=1 make


Building the tool chain from scratch is out of NodeMCU's scope. Refer to ESP toolchains for related information.


If you decide to build with either the Docker image or the native environment then use Git to clone the firmware sources instead of downloading the ZIP file from GitHub. Only cloning with Git will retrieve the referenced submodules:

git clone --recurse-submodules -b <branch>

Omitting the optional -b <branch> will clone release.

Build Options

The following sections explain some of the options you have if you want to build your own NodeMCU firmware.

Select Modules

Disable modules you won't be using to reduce firmware size and free up some RAM. The ESP8266 is quite limited in available RAM and running out of memory can cause a system panic. The default configuration is designed to run on all ESP modules including the 512 KB modules like ESP-01 and only includes general purpose interface modules which require at most two GPIO pins.

Edit app/include/user_modules.h and comment-out the #define statement for modules you don't need. Example:


TLS/SSL Support

To enable TLS support edit app/include/user_config.h and uncomment the following flag:


The complete configuration is stored in app/include/user_mbedtls.h. This is the file to edit if you build your own firmware and want to change mbed TLS behavior. See the tls documentation for details.


To enable runtime debug messages to serial console edit app/include/user_config.h



LFS is turned off by default. See the LFS documentation for supported config options (e.g. how to enable it).

Set UART Bit Rate

The initial baud rate at boot time is 115200bps. You can change this by editing BIT_RATE_DEFAULT in app/include/user_config.h:


Note that, by default, the firmware runs an auto-baudrate detection algorithm so that typing a few characters at boot time will cause the firmware to lock onto that baud rate (between 1200 and 230400).

Double build (Lua 5.3 only)

By default a build will be generated supporting floating point variables (floats) and integers. To increase the precision of the floating point variables, a double build can be created. This is also the default in the Lua 5.1 builds. The downside is that more memory is consumed when storing variables. You can change this either by uncommenting LUA_NUMBER_64BITS in app/include/user_config.h:

//#define LUA_NUMBER_64BITS

OR by overriding this with the make command


Integer build (Lua 5.1 only)

By default a build will be generated supporting floating-point variables (doubles). To reduce memory size an integer build can be created. You can change this either by uncommenting LUA_NUMBER_INTEGRAL in app/include/user_config.h:


OR by overriding this with the make command as it's done during the CI build:


Tag Your Build

Identify your firmware builds by setting the environment variable USER_PROLOG. You may also edit app/include/user_version.h. The variable USER_PROLOG will be included in NODE_VERSION_LONG.


#ifndef BUILD_DATE
#define BUILD_DATE      "unspecified"

u8g2 Module Configuration

Display drivers and embedded fonts are compiled into the firmware image based on the settings in app/include/u8g2_displays.h and app/include/u8g2_fonts.h. See the u8g2 documentation for details.

ucg Module Configuration

Display drivers and embedded fonts are compiled into the firmware image based on the settings in app/include/ucg_config.h. See the ucg documentation for details.