B4R – Easily build native Arduino & ESP8266 programs

B4R is a 100% free development tool for native Arduino and ESP8266 programs.
B4R follows the same concepts of the other B4X tools, providing a simple and powerful development tool.
B4R, B4A, B4J and B4i together make the best development solution for the Internet of Things (IoT).


1. Install Arduino IDE (v1.8+)

Arduino IDE: Arduino 1.8.10

If using Arduino 1.8.11 then you need to update rCore library.

2. Install and configure B4R

Download B4R Full Version

Open B4R.

Choose Tools > Configure Paths.

Use the Browse button to locate “Arduino.exe”. It is located in the Arduino IDE installation folder.

Choose Tools > Board Selector and select the board type and serial port.

3. Next Steps

Join our community

Download the beginner’s guide

Use the site search feature (top right corner). It works!


Documentation Index & Online Guides

Example Projects (source code is available in the documentation index)

Tutorials List

B4R Forum

Timer based blink example

Button example

Memory, variables and objects

Data types

Strings and bytes

Timers, loopers and CallSubPlus

External serial connector

Getting Started with ESP8266

Frequently asked questions

Q: Is B4R completely free, including for commercial purposes?

A: Yes.

Q: Can I access the C source code and the generated objects?

A: Yes. The code and the compiled objects are available under the Objects folder.

Q: Are the libraries open source?

A: Yes. B4R libraries are open source (MIT license). The code is available in GitHub.

Q: I’m getting this error on startup: “Application could not be initialized correctly error 0xc0000135”.

A: Install Microsoft .Net Framework 4+

Windows Vista+: .Net Framework 4.5.2.

Windows XP: .Net Framework 4.0.