ESP32 DevKit C V4 Simulator
The 38-pin ESP32 devkit, free in your browser
Simulate Espressif's ESP32 DevKit C V4 online for free: Arduino C++, MicroPython or ESP-IDF on an in-browser ESP32 emulator, every one of the 38 pins wired to a live circuit, WiFi against a virtual access point.
Free plan · No install, no account · Runs in your browser
ESP32 DevKit C V4 at a glance
The DevKit C V4 is Espressif's own ESP32 board and the wider sibling of the DevKit V1: the same dual-core Xtensa chip and peripheral set, with 38 pins instead of 30. The extra rows bring out GPIOs the V1 leaves unbonded, which matters when a project runs out of pins rather than out of MCU. Sketches are interchangeable with the V1 as long as the pin numbers you use exist on both.
- Processor
- ESP32-WROOM-32, dual Xtensa LX6 at 240 MHz
- Memory
- 520 KB SRAM · 4 MB flash
- Emulation
- esp32js (in-browser)
- Languages
- Arduino C++ · MicroPython · ESP-IDF
- Made by
- Espressif · Product page
- Plan
- Free
What you can do with the ESP32 DevKit C V4 simulator
The board on the canvas is the real thing as far as your code is concerned: the same pins, the same buses, the same peripherals, wired to the same 100+ sensors, displays and actuators every other Velxio board talks to.
Arduino C++ sketches
Write a sketch in the Monaco editor with library completion, compile it against the board's own Arduino core and run the real firmware binary. The Serial Monitor is the USB port.
MicroPython
Switch the board to MicroPython from the toolbar and run main.py against the same circuit. Drivers are plain .py files in the workspace, copied onto the board's filesystem before your script starts.
ESP-IDF projects
Build a full ESP-IDF project (v5.5.4) with FreeRTOS tasks, sdkconfig and components, and run it on the emulated chip without a devkit on your desk.
WiFi against a virtual access point
The emulator advertises the Velxio-GUEST network: HTTP servers, MQTT clients and NTP sync in your sketch connect and answer, without leaving the browser.
GPIO, PWM and ADC
Drive LEDs, relays and servos, read buttons and potentiometers, dim with PWM. Every pin follows the board's real pin map, so what works here works on the hardware.
I2C, SPI and UART
Talk to OLEDs, IMUs, ADCs, RTCs and SD cards over the buses the board really has. Bus traffic runs through emulated peripherals, not through a shortcut.
Serial Monitor
USB CDC serial reaches the Serial Monitor at the sketch's baud rate, with input, timestamps and a plotter.
SPICE analog parts
Op-amps, transistors, regulators and passives simulate in real time with ngspice in the browser; the board's pins drive them and read the solved voltages back.
Multi-board canvas
Mix this board with an Arduino, an ESP32 or a Pico on the same canvas and let them talk over serial or I2C, each running its own firmware.
ESP32 DevKit C V4 examples
This board has no examples of its own yet. These are written for the ESP32 DevKit devkit, which uses the same chip: they run on the ESP32 DevKit C V4 after a pin map check.
ESP32: SSD1306 OLED (4-pin I2C)Drive the cheap 4-pin SSD1306 OLED module (GND/VCC/SCL/SDA) over I2C from an ESP32 (SDA=21, SCL=22).
ESP32 + MicroPython: use an external libraryHow a MicroPython project uses a library in Velxio: there is no requirements.txt and no package manager — the driver is a .py file in the workspace. Every file here is copied onto the board's filesystem before main.py runs, so `import ssd1306` picks up the ssd1306.py next to it and draws on the wired OLED. The toolbar's Library Manager installs ARDUINO libraries and has no effect in MicroPython mode.
ESP32: Pure ESP-IDF BlinkBlink an LED from a pure ESP-IDF project — app_main(), FreeRTOS delays and the GPIO driver, no Arduino core. Pick "ESP-IDF" in the language selector to write more projects like this.
ESP32: Stepper + A4988Spin a bipolar stepper motor from an ESP32 through an A4988 driver (STEP = GPIO26, DIR = GPIO27).
ESP32 Blink LEDBlink the built-in LED on GPIO2 and an external red LED on GPIO4. Verifies ESP32 emulation is working.
ESP32 NeoPixel coloursThe same pixel on an ESP32. Adafruit_NeoPixel drives it through the RMT peripheral here, so the pad never toggles at bit rate and the engine hands the decoded frame to the part.
ESP32 Serial EchoESP32 reads from Serial and echoes back. Demonstrates multi-UART and Serial Monitor integration.
ESP32: 7-Segment CounterCount 0–9 on a 7-segment display driven from GPIO 12, 13, 14, 25, 26, 27, 32 on the ESP32.
Related simulators
Frequently asked questions
- Is the ESP32 DevKit C V4 the same as the DevKit V1 in the simulator?
- Same chip, same emulator, same three languages. The difference is the pin map: the V4 exposes eight more GPIOs, so a project written for it may not fit on a V1 without moving pins. The board reference page lists every pin.
- Does WiFi work on the simulated DevKit C V4?
- Yes. The emulator advertises the Velxio-GUEST access point; WiFi.begin() associates, and HTTP servers, MQTT clients and NTP sync in your sketch run without leaving the browser.
- Can I run ESP-IDF projects on it?
- Yes. Switch the board to ESP-IDF from the toolbar and build a full project with FreeRTOS tasks, sdkconfig and components against ESP-IDF v5.5.4.
- Is the ESP32 DevKit C V4 simulator free?
- Yes. The ESP32 DevKit C V4 runs on the free plan: open the editor, place the board and press Run. No install and no account are needed, and Velxio's editor and simulator core are open source under the GNU AGPLv3.
- Which languages can I use on the ESP32 DevKit C V4?
- Arduino C++, MicroPython, ESP-IDF. The language is switched from the toolbar; the circuit on the canvas stays the same.
Ready to simulate the ESP32 DevKit C V4?
Open the editor, place the ESP32 DevKit C V4 from the picker, wire what you need and press Run.
Launch the ESP32 DevKit C V4 simulator →