The ElectronicsDIY Online Serial Monitor is a free browser-based tool for communicating with USB serial devices such as Arduino, ESP32, STM32, USB-to-TTL converters, and other microcontroller boards. It allows you to connect directly to a serial/COM port, receive data, and send commands without installing a separate serial terminal application. Choose the required COM port, baud rate, data bits, parity, stop bits, and flow control, then connect your device and start monitoring serial communication. The tool supports both Text and HEX modes for receiving and transmitting data, making it useful for debugging firmware, testing sensors and modules, and working with AT-command devices.You can also use features such as auto-scroll, timestamps, pause, clear, command history, and configurable line endings for more convenient serial debugging.
This tool currently works only on Chromium-based desktop browsers that support the Web Serial API, such as Google Chrome, Microsoft Edge, and other compatible Chromium browsers. It is not supported by Firefox or Safari.
Select the baud rate, click Connect, and select your serial device to start.
Disconnected RX 0 B TX 0 B Press Ctrl + Enter to send. In HEX mode enter bytes separated by spaces, e.g. 41 54 0D 0A. No commands sent yet. History is kept only for this browser tab and is cleared when the tab is closed. Serial data is handled locally in your browser and is not uploaded to ElectronicsDIY. Text mode decodes received bytes as UTF-8; invalid bytes are shown as � and control characters as symbols such as ␀. HEX mode shows every received byte as two hexadecimal digits, 16 bytes per line, and starts a new line after a short pause in the data. When sending in HEX mode, enter bytes such as 41 54 0D 0A; they are transmitted exactly as entered and no line ending is added.Connection
Receive
Send
Command History
How to use
Text and HEX modes
Browser requirements
Troubleshooting
