The Arduino environment can be extended through the use of libraries, just like most programming platforms. Libraries provide extra functionality for use in sketches, e.g. working with hardware or manipulating data. To use a library in a sketch, select it from Sketch > Import Library.
A number of libraries come installed with the IDE, but you can also download or create your own. See these instructions for details on installing libraries. There's also a tutorial on writing your own libraries. See the API Style Guide for information on making a good Arduino-style API for your library.

Standard Libraries

  • EEPROM - reading and writing to "permanent" storage
  • Ethernet - for connecting to the internet using the Arduino Ethernet Shield, Arduino Ethernet Shield 2 and Arduino Leonardo ETH
  • Firmata - for communicating with applications on the computer using a standard serial protocol.
  • GSM - for connecting to a GSM/GRPS network with the GSM shield.
  • LiquidCrystal - for controlling liquid crystal displays (LCDs)
  • SD - for reading and writing SD cards
  • Servo - for controlling servo motors
  • SPI - for communicating with devices using the Serial Peripheral Interface (SPI) Bus
  • SoftwareSerial - for serial communication on any digital pins. Version 1.0 and later of Arduino incorporate Mikal Hart's NewSoftSerial library as SoftwareSerial.
  • Stepper - for controlling stepper motors
  • TFT - for drawing text , images, and shapes on the Arduino TFT screen
  • WiFi - for connecting to the internet using the Arduino WiFi shield
  • Wire - Two Wire Interface (TWI/I2C) for sending and receiving data over a net of devices or sensors.

The Matrix and Sprite libraries are no longer part of the core distribution.

101 Only Libraries

  • CurieBLE - Interact with smartphones and tablets with Bluetooth Low Energy (BLE).
  • CurieIMU - Manage the on-board accelerometer and gyro.
  • CurieTimerOne - Allows to use Timer functions.
  • CurieTime - Allows to control and use the internal RTC (Real Time Clock)

Due Only Libraries

  • Audio - Play audio files from a SD card.

Due, Zero and MKR1000 Libraries

  • USBHost - Communicate with USB peripherals like mice and keyboards.
  • Scheduler - Manage multiple non-blocking tasks.

Zero and all the SAMD21 based MKR boards libraries

  • AudioFrequencyMeter - Sample an audio signal and get its frequency back
  • AudioZero - Play audio files from a SD card
  • RTC - Real Time Clock to schedule events
  • ArduinoSound - A simple way to play and analyze audio data
  • I2S - To use the I2S protocol on SAMD21

WiFi 101 and MKR1000 Library

  • WiFi101 - library to be used only with Wifi shield 101
  • WiFi101OTA - Over-the-air updates on MKR1000

MKR WiFi 1010, MKR VIDOR 4000, Arduino NANO 33 IoT and Arduino UNO WiFi Rev.2

  • WiFi NINA - library to use the WiFi Nina module of the above boards.

Arduino Nano 33 BLE, Nano 33 BLE Sense, NANO 33 IoT, Uno WiFi Rev 2, MKR WiFi 1010.

  • ArduinoBLE - library to use the BLE features of the above boards.

Arduino Nano 33 IoT and UNO WiFi Rev. 2

  • ArduinoLSM6DS3 - library to use the LSM6DS3 6 axis IMU available on the Arduino Nano 33 IoT and the Arduino UNO WiFi Rev. 2.

Arduino Nano 33 BLE and BLE Sense

  • ArduinoLSM9DS1 - library to use the LSM9DS1 9 axis IMU available on the Arduino Nano 33 BLE and the Arduino Nano 33 BLE Sense.

Arduino Nano 33 BLE Sense

  • PDM - library to use the digital microphone MP34DT05, our library PDM can be used also with our ArduinoSound library.
  • ArduinoAPDS9960 - library to use the gesture sensor APDS9960; it senses gesture, color, ambience illumination and proximity.
  • ArduinoLPS22HB - library to use the barometer and temperature sensor LPS22; it is an ultra-compact sensor which functions as a digital output barometer.
  • ArduinoHTS221 - library to use the relative humidity sensor HTS221; it is an ultra-compact sensor that uses a polymer dielectric planar capacitor structure capable of detecting relative humidity variations, returned as digital output on a serial interface.

MKR Motor Carrier Only Library

MKR FOX 1200 only Library

  • SigFox - library to be used only with MKRFOX1200

MKR WAN 1300 only Library

  • MKRWAN - library to be used only with MKR WAN 1300

MKR GSM 1400 only Library

  • MKRGSM - library to be used only with MKR GSM 1400

MKR NB 1500 only Library

  • MKRNB - library to be used only with MKR NB 1500

MKR 1000, MKR WiFi 1010, MKR GSM 1400, MKR NB 1500, MKR RS485 Shield, UNO WiFI Rev.2, Ethernet Shield only Library

  • Arduino Modbus - library to communicate with Modbus Protocol over RS485 and TCP with Modbus clients and servers.

MKR GPS Shield Library

  • ArduinoMKRGPS - library to be used with the Arduino MKR GPS Shield

MKR RGB Shield Libraries

  • ArduinoMKRRGB - library to be used with the Arduino MKR RGB Shield
  • ArduinoGraphics - library with graphic primitives, works also with the MKR RGB Shield

MKR 485 Shield Libraries

  • ArduinoRS485 - library that implements RS485 on the Arduino MKR RS485 shield

MKR ENV Shield Library

  • ArduinoMKRENV - library to read all the values measued by the Arduino MKR ENV Shield sensors

MKR THERM Shield Library

  • ArduinoMKRTHERM - library to read the sensors connected to the Arduino MKR THERM Shield

Esplora Only Library

  • Esplora - this library enable you to easily access to various sensors and actuators mounted on the Esplora board.

Arduino Robot Library

  • Robot - this library enables easy access to the functions of the Arduino Robot.

Yún devices Library

  • Bridge Library - Enables communication between the Linux processor and the microcontroller on the Yún.
  • Ciao Library - Aims to simplify interaction between microcontroller and Linino OS allowing a variety of connections with most common protocols

USB Libraries (Leonardo, Micro, Due, Zero and Esplora)

  • Keyboard - Send keystrokes to an attached computer.
  • Mouse - Control cursor movement on a connected computer.