PrintGuard watches your 3D printer cameras with an on-device vision model, pauses the printer the moment a print starts to fail, and sends a snapshot to your phone. No cloud, no subscription, no account — your camera frames never leave hardware you own.

Try it now — nothing to install

oliverbravery.github.io/PrintGuard runs the entire engine in your browser. Point your webcam at a print and watch it score each frame live. Nothing is installed and no frame leaves your device. When you're ready to run it for real, jump to Quick start.

What you get

• Failures caught early — a compact vision model scores every frame and acts the moment a defect holds, so spaghetti and detachments don't run for hours (or burn through a spool).
• Damage stopped for you — a sustained defect can pause or cancel the print through OctoPrint, Klipper, Elegoo, Prusa (PrusaLink) or Bambu Lab, with sensitivity, thresholds and cooldowns you set per monitor.
• A heads-up on your phone — the instant a defect holds, a snapshot lands over ntfy, Telegram or Discord.
• Quiet when nothing's wrong — printers linked to a service are only watched while they actually print; inference rests when they're idle and wakes when a job starts.
• Loud when something is — a dropped camera, frozen feed or unresponsive printer warns you on the dashboard and your phone. If PrintGuard can't tell whether a printer is printing, it keeps watching — losing the signal never silently stops monitoring.
• Every printer on one screen — one machine shares inference fairly across as many cameras as your hardware can sustain.

Make it yours

Choose a look — System, Light, Dark, or design your own in the built-in theme editor — from the header. Your themes are saved and synced to every browser that opens the hub.

Dark	Light

Tap Customise to arrange the dashboard around how you work: drag monitors into any order, pin the ones that matter to the front, and hide the rest — with a tray to bring them back. The camera rail rearranges the same way.

Open any monitor for its live risk score, score history and one-tap printer controls.

Quick start

Desktop app — macOS & Windows

The easiest way to run a hub on the computer next to your printer: a native app — no Docker, no terminal. It lives in your menu bar / system tray, so closing the window leaves the hub running and the printer watched; quit from the tray when you're done. Reach it from your phone on the same network at http://<computer>:8000. Nothing leaves your machine.

Turn on Start at login from the tray menu and forget about it. The builds are unsigned for now, so the first launch needs one manual approval: on macOS, double-click the app, then open System Settings → Privacy & Security and click Open Anyway under Security; on Windows, choose More info → Run anyway. On Linux, run the Docker hub instead.

Docker — for an always-on server or NAS

PrintGuard is a single container — install with one command:

docker run -d --name printguard --restart unless-stopped \
  -p 8000:8000 -p 8554:8554 -p 1935:1935 \
  -v printguard:/data \
  ghcr.io/oliverbravery/printguard

Open http://<host>:8000, pick a mode, register a camera and your printer, then add a monitor that binds them.

• Unraid — add PrintGuard from Community Applications (or import the template) and install from the UI; no terminal needed.
• Docker Compose — prefer a file? docker-compose.yaml: curl -fsSLO https://raw.githubusercontent.com/oliverbravery/PrintGuard/main/docker-compose.yaml && docker compose up -d.

Ports 8554/1935 only matter for cameras that push a stream into PrintGuard — most setups (URL pull, Bambu, or "this device") can leave them off. Images for amd64 and arm64 (Raspberry Pi 4/5) are published to ghcr.io/oliverbravery/printguard on every release.

Two modes, one engine

The same detection engine runs in two places — try it instantly in the browser, then self-host it when you're ready.

The desktop app (macOS and Windows) is hub mode without the setup — the same persistent engine as the container, in a native window on (and never leaving) your own computer.

Printers, cameras and alerts

Register your printer — OctoPrint, Klipper (Moonraker), Elegoo, Prusa (PrusaLink) or Bambu Lab — bind it to a monitor, and choose what a sustained defect does: alert, pause or cancel. If a printer exposes a webcam, PrintGuard adds it as a camera for you. Turn on ntfy, Telegram, Discord, or (in the desktop app) native OS notifications in Settings to get snapshot alerts and watchdog warnings.

Connecting over Docker or HTTPS, or linking an Elegoo, Prusa or Bambu printer, has a few gotchas — the full walk-through (and webcam/camera options) lives in docs/printers.md.

Exposing a hub safely

PrintGuard ships no auth, so put an identity layer in front before anything leaves your trusted network — never port-forward the hub's ports directly. docs/deployment.md has step-by-step setups for Tailscale (recommended), Cloudflare Tunnel + Access and oauth2-proxy, plus a hardening checklist.

Home Assistant

Point the hub at your MQTT broker (Settings → Home Assistant) and every monitor appears in Home Assistant automatically through MQTT discovery — a defect sensor, defect score, the latest failure snapshot, an Enabled switch, and, for linked printers, live status with Pause, Resume and Cancel. Control is two-way, so your automations can drive PrintGuard. The broker is yours and the bridge runs on the hub, so no frames leave your hardware.

Automate it — MCP and API

A hub exposes its engine to agents and scripts through the same protocol the dashboard uses, so anything the UI can do is automatable. Point an MCP client (Claude, an IDE) at https://<host>/mcp/, or use the REST API at /api/v1 — both can read printer and camera status, fetch the current camera frame as an image, and pause/resume/cancel. Capability is per token: issue scoped bearer tokens (read ⊂ control ⊂ manage) from Settings, and an agent only gets what you grant. Full reference: docs/api.md.

How it works

The detector is a ShuffleNetV2 encoder classified by nearest prototype, trained for few-shot FDM fault detection in Edge-FDM-Fault-Detection (with an accompanying technical paper). The sensitivity and threshold sliders map straight onto the prototype distances, so you can tune for your camera and lighting without retraining.

For developers

• docs/architecture.md — how one engine runs on CPython and in the browser, the platform contract, the scheduler and the fail-safe design, with diagrams.
• docs/printers.md — connecting printers and cameras, and the networking gotchas (Docker, CORS, HTTPS, Bambu).
• docs/api.md — the hub's MCP server and REST API: scoped access tokens, every endpoint and tool, and client setup.
• CONTRIBUTING.md — dev setup, tests, and step-by-step guides for adding printer integrations and notification providers.