−50% Launch offer: a Termethos license for $49 $24.50, one-time, until December 31, 2026
Termethos by AstroPearls

Built-in MCP server · Serial terminal for Windows and Linux

Give AI Agents the Power to Debug Real Hardware.

Termethos bridges AI coding agents and embedded systems through a built-in MCP server. Connect Claude Code and other AI agents to real devices for intelligent debugging, live monitoring, and hardware interaction.

Your AI writes the firmware. Termethos connects it to the hardware.

Download Termethos See It in Action

$49 $24.50 one-time purchase −50% until December 31, 2026

  • Free trial in simulation mode
  • No subscription
  • Windows and Linux · v2.0.0

AI agents

  • Claude Code
  • Cursor
  • VS Code
  • Any MCP client

Devices

  • ESP32
  • ESP8266
  • STM32
  • RP2040
  • Arduino
  • Any UART

How it works

The missing link between your AI agent and your board

Your agent already reads and writes your firmware source. Termethos gives it a way to see and talk to the device that runs it.

AI coding agents

Claude CodeCursorVS CodeOther MCP clients

Termethos on your computer

MCP server Trace Dashboard Quick commands & scripts Connections

Embedded devices

ESP32STM32RP2040ArduinoOther devices
AI agents talk to the Termethos MCP server over MCP on your own computer. Termethos talks to the embedded device over the serial port. Data flows both ways: commands go down to the device and its output comes back up to the agent.

What agents can do through Termethos

  • Read and search serial logs read_trace

    The newest lines, only lines after a cursor, only warnings and errors, or lines matching a regular expression. Up to 50,000 lines are kept by default.

  • Wait for events wait_for_trace

    Wait up to 60 seconds for a line such as a boot banner or ready, instead of polling.

  • Query live telemetry read_dashboard

    All 24 dashboard fields, when each one last changed and which changed last.

  • Send commands to the device send_command

    Sends a command with your line ending and returns the lines the device printed in reply.

  • Run quick commands and scripts run_quick_command

    Runs your saved quick commands, including JavaScript scripts that set DTR and RTS to reset a board, if you allow scripts.

  • Create and manage connections create_connection · update_connection · connect

    Creates connections and sets their port, baud rate and serial settings, switches between them, and opens or closes the port, for example around a flash.

You choose what agents may do: read, send commands, run scripts, connect and disconnect, create and edit connections. All tools

Pillar 1

AI-powered embedded debugging

The MCP server is built into Termethos, so there's nothing else to install. Turn it on, add it to your agent with one command, and ask in plain language.

Built-in MCP server

Runs inside Termethos, on 127.0.0.1 only, with a token for every request. It's off until you turn it on.

Claude Code in one command

The setup dialog shows a ready-to-run claude mcp add command with your port and token. Claude Code guide

Other MCP agents too

Cursor and VS Code work with a few lines of JSON, and so does any client that supports Streamable HTTP. Setup for each

Diagnosis from real output

The agent reads leveled log lines and live values from the board, not a summary you typed, and checks its fix after you flash.

You stay in control

Choose what agents may do: read, send commands, run scripts, connect, or create and edit connections. Every agent command shows as [agent] in the history.

terminal · add Termethos to Claude Code
claude mcp add --transport http termethos http://127.0.0.1:7471/mcp --header "Authorization: Bearer <token>"
Claude Code · example prompts
# read only
Read the last 200 trace lines and tell me why the I2C sensor stops answering.

# with commands allowed
Run the "Reset board" quick command, wait for "ready",
and tell me if any errors were printed during boot.

# after flashing your fix
Wait for the boot banner, then check the dashboard:
is field 4 (free heap) still dropping?

Try it with your agent today. Simulation mode is free, no board needed.

Download Termethos Buy $24.50 one-time
Pillar 2

An advanced serial terminal, with or without AI

Everything your agent uses, you get first: a serial terminal built for long debugging sessions on real boards.

Termethos serial terminal with the 24-field telemetry dashboard on top, color-coded trace levels in the middle, and quick command buttons and command history at the bottom

Structured trace levels

Prefix a line with !I, !W or !E and it's colored as info, warning or error. ANSI colors work too.

Live telemetry dashboard

Print @{3:21.5} and field 3 shows 21.5. 24 fields, with the last change highlighted, and the trace stays clean.

JavaScript commands

Quick commands can run a script with the serial port, to send test sequences or raw bytes, or to toggle DTR and RTS.

Hotkeys and command history

Bind commands to buttons and keys, like an emergency stop on space. Sent commands are kept in the history.

Custom baud rates and line control

Standard and custom baud rates such as 74880, and DTR and RTS states chosen per connection, so an Arduino doesn't reset when you connect.

Saved connections

Keep a profile for each board and switch in one click. Termethos reconnects by itself after a reset or re-plug.

Export and Copy for AI

Save a session as .log or .jsonl with millisecond times, or copy a Markdown summary to paste into any AI chat.

Readable at a glance

Boxed banners, alternating line shading and error highlighting make the important line stand out in a fast log.

main.c · works with the printf() you already have
// DBG_LogLn() is just printf() + newline
DBG_Log("\x1b[2J");            // clear trace
DBG_LogLn("!#MicroBot Firmware v1.0");
DBG_LogLn("!ISystem initialization started");
DBG_LogLn("!WSensor 1 data lost");
DBG_LogLn("!EError initializing device");
DBG_Log("@{8:21}");              // dashboard field 8
All serial terminal features

See it in action

From Firmware to Hardware — Close the AI Debugging Loop.

Without Termethos you are the bridge: you flash, copy the log, paste it back and repeat. With it, the agent reads the board itself.

  1. 1

    You

    Ask about the bug

    In Claude Code: “The ESP32 reboots right after Wi-Fi connects. Find out why.”

  2. 2

    Agent → Termethos

    Read the device

    The agent calls read_trace with level: "error" and reads the lines around the reboot, through the connection you have open.

  3. 3

    Agent

    Analyze logs and telemetry

    It compares the reset reason in the log with values on the dashboard from read_dashboard, such as supply voltage or free heap.

  4. 4

    Agent → Device

    Run diagnostics

    It sends diagnostic commands with send_command, or runs a quick command such as your reset script, and reads the reply.

  5. 5

    Agent

    Propose a fix

    It explains the cause and proposes or edits the change in your firmware source, in your editor.

  6. 6

    Agent → Termethos

    Flash and verify

    The agent frees the port with disconnect, flashes the fix, reconnects, waits for the boot banner with wait_for_trace and checks that the errors are gone.

Example agent sessionillustration
> The ESP32 reboots right after Wi-Fi connects. Find out why.

termethos · read_trace  level: "error", lines: 50
  → lines with the reset reason, cursor 18342

termethos · read_dashboard
  → 24 fields, last changed: 4

termethos · send_command  "heap", waitMs: 1000
  → sent: true, the device's reply lines

  … the agent explains the cause, edits and flashes the firmware …

termethos · wait_for_trace  pattern: "ready", since: 18342
  → matched: true
termethos · read_trace  level: "error", since: 18342
  → lines: [] (no errors since boot)

The tool names and parameters are the real ones. What they return depends on your device.

How the flash-and-verify loop works

Who it's for

Built for people who work with real boards

Embedded firmware engineers

Debug microcontrollers with leveled logs and a live dashboard, and turn diagnostic steps into quick commands and scripts that run the same way every time.

AI-assisted developers

Connect Claude Code, Cursor or VS Code to the board on your desk, so the agent checks its firmware changes on real hardware instead of guessing.

IoT developers

Watch sensor readings and connection state on the dashboard, keep a profile per device, and export sessions for a bug report.

Robotics developers

Inspect controller output while motors run, bind start and stop commands to hotkeys, and let an agent read the trace during a test.

Makers and hobbyists

A friendlier serial monitor for ESP32, RP2040 and Arduino projects, with AI integration there when you want it.

Working on an ESP32?

Serial monitor settings, a reset script and the agent loop for ESP32 boards.

Why Termethos

Less copy-paste, more verified fixes

Many terminals show serial output, and some have dashboards or scripting. Termethos puts them in one place, and gives your AI agent direct access to all of it.

The usual loop With Termethos
Copy the log from a terminal and paste it into the chat, again after every run The agent reads the trace itself, filtered to the lines that matter
Tell the agent what the sensor values were The agent reads the live dashboard, with when each value last changed
Type the reset and test commands by hand while the agent waits The agent sends commands and runs your quick commands, if you allow it
Hope the fix worked, and check the board yourself The agent waits for the boot banner and confirms there are no new errors
Switch between a serial monitor, a plotter and a notes file Trace, dashboard, commands, scripts and export in one window

Pricing

One price. No subscription.

Termethos — $49 one-time purchase, now $24.50 with 50% off. Try everything free first.

Simulation mode

Freeno license needed

Download Termethos and try the whole app with a simulated device. Set up your AI agent against the simulated trace and dashboard before you buy.

  • Every feature, with a simulated device
  • MCP server with simulated data
  • No board, no account, no card
Download free

Termethos license

$24.50$49one-time purchase

50% off until December 31, 2026. The code APTERM50 is applied for you at checkout.

Unlock real serial ports, so you and your AI agent work with the actual hardware.

  • One license key for two computers
  • Includes all 2.x updates
  • No subscription, nothing renews
  • Real serial ports and agent commands to your device
Buy a license for $24.50

Secure checkout by Polar, our reseller. Any sales tax or VAT is shown before you pay. For Windows and Linux.

License details

FAQ

Questions, answered

What is Termethos?
A serial terminal for Windows and Linux, built for embedded and IoT development, with a built-in MCP server. You get color-coded trace levels, a 24-field live dashboard, quick commands with hotkeys and JavaScript scripts. AI coding agents such as Claude Code can use it to read the trace and dashboard, send commands to your device and set up connections.
Does it require an AI agent?
No. Termethos is a complete serial terminal on its own, and the MCP server is off until you turn it on. You can use it just for its trace, dashboard and commands, and turn agents on later.
Which AI agents are supported?
Termethos has setup instructions for Claude Code, Cursor and VS Code. Other MCP clients work too if they can connect to an MCP server over Streamable HTTP and send an Authorization header.
What is MCP?
The Model Context Protocol is an open standard that lets AI agents use tools and data outside the chat. Termethos runs an MCP server, so an agent can call tools such as read_trace, read_dashboard and send_command on the connection you have open. See all tools
Which embedded devices can it communicate with?
Any device that shows up as a serial port, a COM port on Windows or /dev/ttyUSB… or /dev/ttyACM… on Linux, directly over USB or through a USB-to-serial adapter. That includes ESP32, ESP8266, STM32 (through an ST-LINK virtual COM port or a USB-UART adapter), RP2040 and RP2350, Arduino boards and most other microcontrollers. You can add custom baud rates, such as 74880.
Can I use Termethos as a traditional serial terminal?
Yes. Pick a port and baud rate, connect, read the output and type commands. The trace levels, dashboard and quick commands are optional extras that work with the printf() output you already have.
Does the MCP server run locally?
Yes. It runs inside Termethos on your computer, listens only on 127.0.0.1 and needs a token for every request, so other computers can't reach it. Termethos doesn't send your serial data anywhere. Keep in mind that the AI agent you connect sends what it reads to its own model provider, as it does with the rest of your code.
What does the $49 license include?
A license key for two computers, for a one-time payment. It includes all 2.x updates, and there's no subscription, so nothing renews. Without a license Termethos runs in simulation mode for free, with a simulated device, so you can try the app and your AI agent before you buy.
All questions

Give your AI agent a real board to work with

Download Termethos and try it free in simulation mode. When you're ready, a one-time $24.50 license unlocks real serial ports, 50% off its usual $49 until December 31, 2026.

Download Termethos Buy $24.50