Web Serial Terminal

A serial monitor that runs in the browser, with nothing to install.

The terminal uses the Web Serial API, which lets a page talk to a serial port after you pick the device in a browser dialog. When opening the port, the browser requires the baud rate and accepts 7 or 8 data bits (default 8), 1 or 2 stop bits (default 1), parity none, even or odd (default none) and flow control none or hardware (default none). The 8N1 format is 8 data bits, no parity and 1 stop bit. The baud rate must equal the firmware's: with Serial.begin(9600) in the code, use 9600, and mismatched values show up as meaningless characters. Incoming data is assembled into lines on LF, CRLF or CR, shown as text or hexadecimal with an ASCII column, and stamped with the time of its first byte. ANSI color codes, common in ESP logs, can be stripped from the display. To send, choose the line ending (LF, CR, CRLF or none), type text or bytes in hexadecimal and use the arrow keys to repeat earlier commands. The log keeps at most 5,000 lines or 8 MB and drops the oldest, so a long session does not eat the tab's memory, and it can be saved as .txt or .csv. Nothing opens by itself: the port is requested only when you click Connect, and if the cable is pulled the tool says so and offers Reconnect. The data only passes through your browser.

Pick the baud rate, connect and talk to the board.

1. Pick the baud rate that matches your code and click Connect. The browser shows the list of ports: select the board's. Open Port options only if you need other bits, parity or flow control.
2. Watch incoming data as Text or Hex, with timestamps. Pause the display to read without losing data, strip the ANSI colors and turn auto-scroll on or off.
3. Type a command and press Enter, choosing the line ending, or send bytes in Hex. Save the log as .txt or .csv and disconnect when you are done.

Cite or link to this tool

<a href="https://jkit.tools/en/tools/web-serial-terminal">Web Serial Terminal</a>

Sources and references for this tool

These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.

• Web Serial APIMDN Web Docs, API overview, secure-context requirement and port reading.
• SerialPort: open() methodMDN Web Docs, Baud rate, data bits, parity, stop bits and flow control options, with defaults.
• Web Serial API browser supportCan I use, Browser support table for the Web Serial API.
• Arduino reference: Serial.begin and Serial.printlnArduino, Reference for Serial.println (CR and LF at the end) and Serial.begin (SERIAL_8N1 default).

Frequently asked questions

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