hwcast

hwcast

A tiny Windows service that serves a live hardware dashboard for your PC to any browser on your network: CPU, every NVIDIA GPU, RAM, page file, motherboard temperatures, fans and the apps using the most resources, updated every second. It also feeds the same data to AI agents through a built-in MCP server and to mods like small displays.

Nothing to install on the viewing device. Open the address in any browser on your local network (a laptop, a spare monitor, a tablet, a phone) and leave it open.

The same live data goes beyond the browser:

• AI agents (MCP): a built-in MCP server lets Claude Code, Codex, Cursor and other agents read your hardware, find a free GPU or wait for a job to finish.
• Mods: separate programs can subscribe to the stream and show it anywhere, like the GCB200 bracket display mod.

Try the live demo: the real dashboard running on made-up data, right in your browser.

Features

• One exe, one double-click: installs itself as a Windows service that starts at boot. No installer framework, no runtime.
• Every GPU detected automatically: each NVIDIA card gets its own panel and graph, numbered the same way as nvidia-smi.
• Real sensors: CPU temperature and package power, motherboard temperatures, fans and your own thermistor probes, read directly through the signed PawnIO driver.
• Costs nothing when nobody is watching: sensors are only read while a dashboard is open. 0% CPU and about 0.2 MB of RAM otherwise.
• Local network by default: any device at home can open it, nothing is exposed to the internet. Works through Tailscale or any VPN for access from elsewhere.
• Mods: a versioned live stream that other programs can build on: small displays, LED strips, home automation. See Mods.
• Built for AI agents too: an MCP server is built in, so Claude Code, Codex, Cursor and other agents can check temperatures, find a free GPU or wait for a job to finish. See hwcast for AI agents.
• Plain commands: hwcast status, start, stop, open, uninstall. Start and stop need no admin prompt.

Quick start

Option 1: download and double-click

1. Download hwcast.exe from the latest release.
2. Double-click it, answer Y, and approve the Windows admin prompt.
3. The dashboard opens in your browser. The installer also prints the address to open on your other devices, for example http://192.168.1.20:8340.

Option 2: let your AI coding agent set it up

Click Setup with an agent and pick yours: Claude Code (one click), Codex, Antigravity, Grok Build, or any other agent that can run PowerShell. It starts with a prepared prompt; the agent checks your hardware, asks a few questions (port, where you will view the dashboard, sensor driver, install folder, connecting AI agents) and installs hwcast once you confirm. The steps it follows are in docs/agent-setup.md.

Or paste this prompt into any coding agent yourself:

Set up hwcast on this Windows PC for me. Read the setup guide at https://raw.githubusercontent.com/ShreyamMaity/hwcast/main/docs/agent-setup.md (if you cannot browse, download it in PowerShell with: irm <that URL>) and follow it exactly: check my system first, ask me the setup questions, and wait for my answers before changing anything.

Option 3: winget and MSI are planned for the next release.

Commands

After installing, hwcast works in any new terminal.

Command	Does
hwcast status	Service state, sensor driver, and the dashboard addresses for this PC, your network and your VPN
hwcast open	Opens the dashboard in your browser
hwcast start / stop / restart	Controls the service. Stopping lasts until the next boot
hwcast install [--port 9000] [--dir D:\Tools\hwcast]	Installs or updates. Run a newer hwcast.exe the same way to upgrade; your config is kept
hwcast uninstall [--keep-config]	Removes everything. Also available in Settings > Apps
hwcast run	Runs in the foreground instead of as a service
hwcast mcp	MCP server for AI agents on stdin and stdout. Agents start it themselves, see below
hwcast --once	Prints every sensor as JSON (run as admin). Useful to find sensor IDs

The installer adds a hwcast entry to the Start menu that opens the dashboard, and an entry in Settings > Apps for uninstalling.

Use case: a tablet as a dedicated stats screen

An old iPad, an Android tablet or a spare phone makes a great always-on hardware monitor next to your desk: glance at temperatures and GPU load during a game, a render or a training run without alt-tabbing to Task Manager.

Want to see how it looks first? Open the live demo on the tablet.

1. On the tablet, open the address from hwcast status, for example http://192.168.1.20:8340.
2. Add it to the home screen. On iPad or iPhone: Share, then Add to Home Screen. On Android: browser menu, then Add to Home screen or Install app. It then opens full screen, without browser bars.
3. Keep the screen on. The dashboard asks the browser to keep the screen awake while it is open (tap it once if the screen still dims). On iPad you can also set Settings > Display & Brightness > Auto-Lock > Never, or use Guided Access to lock the tablet to the dashboard.
4. Leave it on its charger. The dashboard reconnects by itself if the PC sleeps or restarts.

The layout adapts from a phone in portrait up to a tablet in landscape. Two GPUs, CPU and memory fit on one iPad mini screen in landscape; in portrait the cards stack and scroll.

Viewing it away from home

hwcast only answers your local network by default. To see it from elsewhere, use whatever you already use to reach your home network.

Optional: Tailscale

Tailscale is the easiest way to keep the dashboard working on your phone or tablet anywhere, with nothing exposed to the internet. hwcast already allows Tailscale addresses, so there is nothing to configure on the hwcast side.

1. Install Tailscale on the PC and on the viewing device, and sign in to the same account on both.
2. Run hwcast status on the PC. It prints a 100.x.y.z address next to "Tailscale / VPN".
3. Open http://100.x.y.z:8340 on the device. With MagicDNS on, http://<your-pc-name>:8340 works too.

The connection is encrypted by Tailscale end to end. Anyone you share your tailnet with can see the dashboard, so use Tailscale ACLs if that matters.

Other options

• Another mesh VPN such as ZeroTier or WireGuard. Addresses in 100.64.0.0/10 are allowed by default; for other ranges, add them to allow in config.json.
• A reverse proxy (Caddy, nginx, Traefik) in front of http://<PC>:8340. Put HTTPS and a login in front of it if it faces the internet, since hwcast has no login of its own.

Footprint

	Measured
CPU while nobody is watching	0% (sensors are not read at all)
Memory while nobody is watching	about 0.2 MB resident
CPU while a dashboard is open	about 1.3% of one core
Memory while a dashboard is open	about 23 MB (mostly the NVIDIA library)
Network	about 1 KB per second per viewer
Download	one exe, about 730 KB

What it shows

• CPU: temperature (Tctl), per CCD temperatures, package power, total and per thread load, 5 minute graph
• GPUs (NVIDIA): temperature, hotspot and memory temperature where the card reports them, load, power vs limit, VRAM, clock and fan speed for every card, each with its own graph
• Memory: RAM used and free, page file in use and peak, commit charge, graph of both
• Board: motherboard temperatures, fan speeds, and external thermistor probes as large tiles
• Top processes: by CPU and by memory, grouped by app the way Task Manager groups them

Requirements

• Windows 10 or 11, x64
• A browser on any device on the same local network (or on the PC itself at http://localhost:8340)
• PawnIO driver for CPU temperature and motherboard sensors. The installer offers to install it with winget. Without it, load, memory, GPUs and processes still work

Hardware support

Part	Supported
CPU temperature and power	AMD Ryzen (Zen 1 to Zen 5)
CPU load, RAM, page file, processes	Any
GPU	NVIDIA, any number of cards (through NVML, ships with the driver)
Motherboard sensors	ITE Super I/O chips: IT8613E, IT8628E, IT8686E, IT8688E, IT8689E, IT8696E, IT87952E, IT8792E (most Gigabyte boards)

Board channels on Gigabyte AM5 boards (X870, X870E, B850 with IT8696E) get proper names. Other supported chips show numbered channels ("IT8686E temp 3") that you can rename in config.json. Unsupported parts are simply hidden on the dashboard.

Not supported yet: Intel CPU temperatures, AMD and Intel GPUs, Nuvoton Super I/O chips (most ASUS, MSI and ASRock boards). Pull requests welcome.

Configuration

Optional config.json in the install folder (default C:\Program Files\hwcast). Run hwcast restart after editing it. See config.example.json.

{
  "bind": ["0.0.0.0:8340"],
  "allow": ["127.0.0.0/8", "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "100.64.0.0/10"],
  "labels": { "it8696e.t5": "Between GPUs" },
  "probes": ["it8696e.t5", "it87952e.t1"],
  "hide": ["it8696e.f5"]
}

Key	Meaning
bind	Addresses to listen on. hwcast install --port sets this for you
allow	IPv4 ranges allowed to connect. Default is this PC, the private LAN ranges and 100.64.0.0/10 (Tailscale and similar VPNs). Narrow it, for example to ["127.0.0.0/8", "192.168.1.0/24"], to allow only your own subnet
labels	Rename any sensor. IDs look like it8696e.t5 (chip, temperature channel 6) or it8696e.f0 (chip, fan 1). hwcast --once lists them all
probes	Sensors to show as large tiles with their own graph, meant for thermistor probes you placed yourself
hide	Sensors to leave out

How it works

sensors (PawnIO, NVML, Windows)  >  hwcast service  >  Server-Sent Events over your network  >  browser

• The service serves one HTML page and a /events stream. The browser keeps that stream open and receives one small JSON update per second, then draws everything locally. History lives in the browser, nothing is written to disk.
• Sensors are read only while at least one viewer is connected. When the last one leaves, the NVIDIA library is unloaded and memory is handed back to Windows.
• CPU and board sensors are read through PawnIO, a signed driver that runs small sandboxed modules for port and register access. hwcast only reads sensors and never writes fan or voltage settings. It holds the same bus locks HWiNFO, LibreHardwareMonitor and vendor tools use, so they can run at the same time.
• No WMI, no polling of other tools, no telemetry of its own.

/api/now returns one JSON snapshot, handy for scripts and home automation. /mcp serves the same data to AI agents (docs/mcp.md).

AI agents (MCP)

hwcast has a built-in MCP server, so AI agents can read your hardware live. It is read only: agents can look, never change anything.

On this PC (Claude Code shown; Codex, Cursor, Claude Desktop and VS Code are in the guide):

claude mcp add --scope user hwcast -- hwcast mcp

From another machine on your network or tailnet:

claude mcp add --scope user --transport http hwcast http://192.168.1.20:8340/mcp

Tool	Does
get_summary	CPU, every GPU, RAM and the busiest apps in one compact reading
get_cpu, get_gpus, get_memory, get_sensors, get_processes	Detail for one area
check_gpu_free	Watches the GPUs for a few seconds and says which one is free for a job that needs a given amount of VRAM
sample	Min, average and max of any metrics over up to a minute
wait_for	Waits until a metric drops below or rises above a value, for example until a render finishes or a GPU cools down
list_metrics, get_snapshot	Every metric name with its value, and the raw snapshot

Setup for every client, metric names and protocol details: docs/mcp.md.

Mods

Mods are separate programs that read the same /events stream and send the data somewhere else: a small display, an LED strip, a home automation hub. hwcast itself stays read only and knows nothing about them. The stream format is versioned and documented in docs/mods.md.

Mod	What it does
hwcast-gcb200	Shows two live values with load bars on the Ant Esports GCB200 GPU bracket display

Built one? Open a pull request that adds it to this table.

Security

• Only this PC, your local network and VPN addresses (100.64.0.0/10) can connect by default. hwcast checks this itself, and the installer's firewall rule enforces it too. Nothing is opened to the internet.
• Read only. There is nothing to control on the dashboard, and the MCP tools for agents only read too.
• The MCP endpoint refuses requests from web pages served by other sites, so a page you visit cannot use it to read your PC.
• No login. Anyone on your local network can see the dashboard (hardware stats and the names of running apps). If that matters, narrow allow in config.json.
• Plain HTTP. That is fine on a home network or inside a VPN tunnel. Use a reverse proxy with HTTPS and authentication if you expose it any further.
• The service runs as LocalSystem because reading CPU and motherboard sensors needs it. Interactive users can start and stop it; only administrators can install, change or remove it.

Tech Stack

Layer	Technology
Language	Rust (2021 edition), single static exe
Sensor access	PawnIO signed driver with PawnIO.Modules
GPU	NVML through nvml-wrapper
Windows APIs	windows-sys, windows-service
Web server	Hand-written HTTP + Server-Sent Events on std::net (no async runtime)
UI	Vanilla HTML/CSS/JS and canvas, embedded in the exe (no build step)

Build from source

git clone https://github.com/ShreyamMaity/hwcast
cd hwcast
powershell -File scripts\fetch-modules.ps1   # downloads the PawnIO modules into vendor\mods
cargo build --release                        # target\release\hwcast.exe

scripts\package.ps1 builds the release assets (hwcast.exe, a zip with the licenses, and SHA256SUMS.txt).

Code signing policy

Releases are not code signed yet, so Windows SmartScreen may warn the first time you run hwcast.exe ("Windows protected your PC"). Click More info, then Run anyway. To check a download yourself, compare Get-FileHash hwcast.exe with the line in the release's SHA256SUMS.txt.

• Every release is built from this repository's source by GitHub Actions on GitHub-hosted runners. Nothing is built or uploaded by hand.
• Team roles:
  • Committers and reviewers: Shreyam Maity
  • Approvers: Shreyam Maity
• Contributions from people outside the team are reviewed before they are merged.

Privacy

hwcast does not send any information to other networked systems. It serves the dashboard only to devices that open it (this PC, your local network and VPN addresses by default) and has no telemetry, analytics or update checks. The only outbound connection is optional and happens during installation, when you agree to install the PawnIO driver through winget.

Credits

• PawnIO and PawnIO.Modules by namazso, for safe sensor access on Windows
• LibreHardwareMonitor, whose Super I/O and Ryzen code this follows
• See THIRD_PARTY_NOTICES.md for licenses

License

MIT. The embedded PawnIO modules are LGPL-2.1, see THIRD_PARTY_NOTICES.md.