Try the Arduino, ESP32, Pico & ESP8266 Pinout
Searchable pinout reference for Arduino Uno/Nano, ESP32 DevKit, Raspberry Pi Pico and NodeMCU ESP8266: PWM, ADC, I²C, SPI, UART pins, strapping pins.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
On an ESP32, pick GPIO32–39 for analog input if Wi-Fi is used (ADC1), keep GPIO34–39 for inputs only, avoid GPIO0/2/12/15 for devices that pull them at boot, and use GPIO21/22 for the default I²C bus.Open the Arduino, ESP32, Pico & ESP8266 Pinout
Illustration. Open the tool for the real thing.
What is the Arduino, ESP32, Pico & ESP8266 Pinout?
Picking pins is where microcontroller projects quietly go wrong: an ESP32 that will not boot because a sensor pulls GPIO12 high, an Arduino whose serial upload fails because D0/D1 are in use, a Pico I²C bus on the wrong pins, an ADC that stops working when Wi-Fi starts. This reference lists the pins of four popular boards — Arduino Uno/Nano, ESP32 DevKit (38-pin), Raspberry Pi Pico and NodeMCU/Wemos D1 (ESP8266) — with what each can do (PWM, ADC, DAC, touch, I²C, SPI, UART, interrupts) and the traps to avoid.
Filter by function (for example 'I2C' or 'ADC') or search for a pin name, and boot-strapping pins, input-only pins, flash pins and USB-serial pins are highlighted. The notes also remind you of the logic level of each board — the ESP32, Pico and ESP8266 are 3.3 V only and not 5 V tolerant — and typical per-pin current limits. It is compiled from the manufacturers' datasheets; check your own board's silkscreen, because clones differ.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Arduino Uno/Nano, ESP32 DevKit, Raspberry Pi Pico, NodeMCU ESP8266.
PWM, ADC, DAC, touch, I²C, SPI, UART, interrupts, power.
Strapping, input-only, flash, USB-serial and boot-state notes.
3.3 V vs 5 V logic and typical pin current limits.
AZRS tools are free to open and use.
It opens in your browser, so there is nothing to download.
Used for
Pick one to see how it fits.
How it compares
A plain look at this tool next to the usual alternative.
| This maker tool | Desktop software | |
|---|---|---|
| Install | Nothing to install | Usually an app or program to install |
| Account | No signup | Depends on the product |
| Cost | Free to use | Free or paid, depends on the product |
| Where it runs | In your browser tab | On your computer |
Questions people ask
Are clone boards the same?
Often yes, but always check the silkscreen and schematic.
Does it include the Mega or STM32?
Not yet — the most-used four boards are covered.
Which pins are safe on the ESP32?
GPIO4, 13, 14, 16–19, 21–23, 25–27, 32, 33 for general use.
Is it free?
Yes.
How do I use the Arduino, ESP32, Pico & ESP8266 Pinout?
1. Choose your board. 2. Filter by the function you need or search for a pin. 3. Read the notes for each pin before wiring. 4. Pick pins that avoid the highlighted warnings.
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Searchable pin functions, PWM/ADC/I²C/SPI pins and boot-strapping warnings for popular. Free to use.
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