thevenom.dev

Comterm

A serial terminal in a browser tab. Plug in a radio, a GPS module or a dev board over USB-serial, pick the port, set the baud and start talking to it. Nothing to install, and the data stays between your browser and the device.

Open the terminal How it works
COMTERM.NFO
Platform
Web (Chrome/Edge desktop)
Price
Free
Licence
None published
Version
1.0.1
Status
Beta
Released
2026-11-05
Last updated
2026-11-06
Signed
N/A (runs in browser)
Publisher
thevenom

Terminal

How it works

  • Your browser picks the port

    Connect opens the browser's own port chooser. Comterm only sees the port you pick, and only until you disconnect or close the tab.

  • Stays on your machine

    Bytes go between the tab and the device. Nothing is uploaded, logged or stored; Save log writes a plain .txt to your downloads.

  • ASCII or hex

    Read NMEA sentences and AT replies as text, or flip to hex to see every byte, CR and LF included. Timestamps are per line, to the millisecond.

Good to know

Works in Chrome and Edge on Windows, macOS, Linux and ChromeOS. Firefox, Safari and phones don't support Web Serial.

Port not in the list? Most cheap USB-serial adapters use a CH340, CP210x or FTDI chip; install the driver for yours. Close any other program holding the port first. On Linux, add yourself to the dialout group.

The frame is fixed at 8N1 with no flow control, which covers almost every radio, GPS and dev board.

Prefer a terminal?

# Windows: PuTTY, Serial, COM3, 115200
putty -serial COM3 -sercfg 115200,8,n,1,N
# macOS / Linux
screen /dev/ttyUSB0 115200
# Python (pyserial)
python -m serial.tools.miniterm /dev/ttyUSB0 115200

How to use it

  1. Open this page in Chrome or Edge on a desktop, over HTTPS.
  2. Plug in your USB-serial adapter or device, pick a baud rate (115200 is the default) and press Connect.
  3. Choose the port in the browser’s own chooser.
  4. Type a line and press Enter to send it. Flip to hex, toggle timestamps or local echo, and use Save log to keep a copy.

Release notes

What’s new

  • 1.0.1 · 2026-11-06
    Stricter browser check: Firefox builds with an experimental serial API now get the clear “can’t open serial ports” panel. Larger tap targets and higher-contrast labels.
  • 1.0.0 · 2026-11-05
    First release: Web Serial terminal with baud picker, ASCII/hex view, timestamps, local echo, CR/LF/CRLF line endings and log save.

Platform support

  • Chrome and Edge on Windows, macOS, Linux and ChromeOS: supported
  • Firefox (including experimental Web Serial builds): not supported
  • Safari: not supported
  • Phones and tablets: not supported
  • Needs HTTPS and JavaScript

Known limitations

  • Frame is fixed at 8N1 with no flow control.
  • No hardware flow control, break signal or DTR/RTS toggles yet.
  • Tested with mocked ports and common USB-serial chips; unusual adapters may need their vendor driver.
  • Beta: report anything odd through the contact form.

Trust. Comterm is a browser tool: nothing to download or install. Bytes go only between this tab and the port you pick; nothing is uploaded or stored on this site. Version 1.0.1.

Comterm is free. If it saved you hunting for a terminal app, a coffee is appreciated.

Buy me a coffee