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Chrome and Word add-ins (sideload)

Two open-source add-ins put the engine where you read and write chemistry. Both talk directly to your own engine: one on this machine, a DGX Spark on your network, or a self-hosted deployment on AWS / Azure / GCP. No hosted account, no API key for a single-user engine.

Chrome extension Word add-in
What it does Detects SMILES on PubChem, ChEMBL, bioRxiv / medRxiv and arXiv pages; hover or click for a profile; side panel with ADMET, compliance and more Highlight a SMILES in your manuscript for the same analysis; Scan Document profiles every SMILES in the doc
Source novomcp-chrome-sideload novomcp-word-sideload
Install Build, then Load unpacked in Chrome Trust a local HTTPS certificate (once per machine), then sideload the manifest
One-time setup per user None Yes: a local dev certificate (see below)

Before you start: have an engine running (see the Quickstart, or DGX Spark) and confirm curl -s http://localhost:8018/health returns {"status":"healthy",...}.

Chrome extension

Install

Prerequisites: Node 18+, Chrome 116+.

git clone https://github.com/NovoMCP/novomcp-chrome-sideload.git
cd novomcp-chrome-sideload
npm install
npm run build

In Chrome, open chrome://extensions, turn on Developer mode, click Load unpacked, and select the dist/ folder.

Connect

Click the NovoMCP toolbar icon:

  • Engine on this machine: leave Engine URL at http://localhost:8018, leave the API key blank, and click Connect.
  • Engine on another machine (a DGX Spark on your network, or a cloud VM): enter its address, e.g. http://spark-xxxx.local:8018, and click Connect. Chrome asks once for permission to reach that host; click Allow.

Use

  • Open a compound page, e.g. PubChem aspirin. Detected SMILES get a dashed underline. In PubChem the canonical one is under Names and Identifiers → Computed Descriptors → SMILES.
  • Hover the underlined text for a preview card, and click it to run the profile. Open in sidebar gives the full tabs (Profile, ADMET, Compliance, …).
  • The extension reacts to SMILES text, not to structure images.

Reload tabs opened before you connected

The extension decorates pages that load after it's connected. A tab that was already open when you clicked Connect shows no underlines until you reload it.

Word add-in

Before you start: trust a local HTTPS certificate (once per machine)

Word loads add-ins only over HTTPS, and the sideload serves its taskpane from your own machine at https://localhost:3000. So every user needs a locally trusted development certificate, once per computer:

git clone https://github.com/NovoMCP/novomcp-word-sideload.git
cd novomcp-word-sideload
npm install
npx office-addin-dev-certs install --days 365
  • It creates a certificate authority on your machine only and trusts it in your keychain (macOS) or certificate store (Windows). You'll be asked for your password. It only vouches for localhost on your computer, so it isn't shared and can't be shared. Each user and each machine runs it once.
  • It expires. The tool's default lifetime is 30 days; --days 365 gives a year. Check it with npx office-addin-dev-certs verify.
  • The Office Store version of the add-in doesn't need this, because it loads from a hosted HTTPS address.

Run

Use two terminals in the repo:

# Terminal 1: serves the taskpane on https://localhost:3000. Keep it running.
npm run dev

# Terminal 2: sideloads the manifest into Word and launches Word
npm run start

In Word: Home → NovoMCP → Open NovoMCP. (If Word didn't launch, open it and use Insert → My Add-ins → Shared Folder.)

Connect

  • Engine on this machine: keep Engine URL at http://localhost:8018 and click Connect.

  • Engine on another machine (e.g. a DGX Spark on your network): Word blocks plain-http calls from its HTTPS taskpane to any host but localhost, so route them through the dev server's built-in proxy:

    NOVOMCP_ENGINE_URL=http://spark-xxxx.local:8018 npm run dev

    and set Engine URL to https://localhost:3000/engine.

  • Engine behind HTTPS (e.g. https://novomcp.your-lab.org): enter that URL directly.

Then highlight a SMILES in your document, e.g. CC(=O)OC1=CC=CC=C1C(=O)O, to see its profile and ADMET.

Remote engines and security

  • Simplest remote setup: an SSH tunnel. ssh -L 8018:localhost:8018 <engine-host> makes a remote engine (a rented Spark, a cloud VM) appear at http://localhost:8018, so both add-ins work on their defaults with no proxy or permission prompt.
  • Don't expose :8018 to the internet. In the default single-user mode (NOVO_AUTH=local) the engine has no authentication. Keep it private (SSH tunnel, VPN or private network), or put it behind HTTPS with auth. See Deploying to the cloud.

Troubleshooting

Word: "The content is blocked because it isn't signed by a valid security certificate" The local dev certificate is missing, untrusted or expired. Check the expiry date: 

openssl x509 -in ~/.office-addin-dev-certs/localhost.crt -noout -enddate
and replace it (asks for your password): 
npx office-addin-dev-certs uninstall && npx office-addin-dev-certs install --days 365
Restart npm run dev, which reads the certificate only at startup, then click Restart in Word's add-in pane.

Word: "Sorry, we can't load the add-in… network connectivity" npm run dev isn't running. The taskpane is served from it, so keep it running while you use the add-in.

Chrome: connected, but no underlines on the page Reload the tab (see the note above), and check that you're on a supported site: PubChem, ChEMBL, bioRxiv / medRxiv, arXiv.

Either: "Network error" / can't connect Check the engine from the same machine: curl -s <engine-url>/health. For an engine on another machine, Chrome needs the one-time Allow prompt, and Word needs the /engine proxy described above.