GluePuddingTool

Web Serial Debugger

Online serial port debugging tool built on the Web Serial API. Connect to a serial device straight from the browser with no driver installation, send commands and watch incoming data in real time.

FreeOnline Tool
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How to Use

  1. Click Connect and choose your target serial device in the browser's device picker.
  2. Set the baud rate (such as 9600 or 115200), data bits, stop bits and parity to match the device.
  3. Click Open to establish the connection. The status bar turns green when it succeeds.
  4. Type a command in the send box, choose ASCII or HEX format, and click Send or press Enter.
  5. The receive area shows returned data in real time, and you can switch it between ASCII and HEX display.
  6. Click Clear to empty the receive area, or Disconnect to close the port.

Note: the Web Serial API works only in Chrome 89+ and Edge 89+, and the page must be served over HTTPS or from localhost.

Features

  • No drivers, no installation: built on the Web Serial API, so Chrome and Edge connect to the port directly with no driver or desktop terminal software.
  • ASCII and HEX modes: both sending and receiving support plain text and hexadecimal, covering different debugging needs.
  • Flexible serial settings: baud rates across the full 300 to 921600 bps range, plus configurable data bits, stop bits and parity.
  • Live receive display: the receive area scrolls with the newest data and can add timestamps for analyzing communication timing.
  • Command history: sent commands are saved automatically so frequently used ones can be resent quickly.

Use Cases

Microcontroller firmware debugging
Connect to the serial port of an Arduino, STM32 or similar board, send AT commands or custom protocol frames and watch the responses live.
Sensor data collection
Connect to GPS modules, temperature and humidity sensors and other serial devices to verify that data format and protocol are correct.
Industrial equipment communication
Talk to Modbus RTU devices and PLCs, sending register read and write commands and inspecting the response frames.
Quick checks during embedded development
Verify serial communication logic straight from the browser without desktop software, speeding up embedded prototyping.

FAQ

Why does no device picker appear when I click Connect?
Check that you are using Chrome 89+ or Edge 89+ and that the page is running over HTTPS or on localhost. Firefox and Safari do not currently support the Web Serial API.
The connection succeeded but no data arrives. What now?
Check three things: whether the baud rate matches the device, whether data bits, stop bits and parity match, and whether the device is actually transmitting, which you can confirm with a multimeter by looking for level changes on the TX pin.
How do I format HEX data when sending?
In HEX mode, enter space-separated hexadecimal bytes such as 01 03 00 00 00 01 84 0A. The tool parses these and sends the corresponding byte stream, and no 0x prefix is needed.
Can I open several serial ports at once?
The current version supports a single connection at a time. To debug multiple devices simultaneously, open the tool in several browser tabs.