ThemysThemys/Docs

Installation Guide

Install the Themys Chrome extension or use the web app. Setup takes under a minute.

System Requirements

RequirementDetails ---------------------- BrowserGoogle Chrome 88+ (Manifest V3 support) OSWindows, macOS, Linux, or ChromeOS AccountFree Themys account (sign up at themys.ca)

Themys is built on Chrome's Manifest V3 platform. Other Chromium-based browsers (Edge, Brave, Arc) may work but are not officially supported.

Option 1: Chrome Extension

From the Chrome Web Store

The production extension is available on the Chrome Web Store.

1. Visit the Chrome Web Store listing

2. Click Add to Chrome

3. Confirm the permissions dialog

4. The Themys icon appears in your toolbar

Load Unpacked (Development)

For local development or testing:

1. Clone the repository and build the extension:

bash
git clone https://github.com/themys/toscaner.git

cd toscaner


pnpm install


pnpm build:extension

2. Open Chrome and navigate to chrome://extensions

3. Enable Developer mode (toggle in the top-right corner)

4. Click Load unpacked

5. Select the extension/dist folder from the cloned repository

The extension will load and appear in your extensions list. To update after code changes, rebuild with pnpm build:extension and click the refresh icon on the extension card.

Option 2: Web App

No installation required. Visit themys.ca in any modern browser.

The web app provides the same analysis capabilities as the extension:

  • Paste a URL to scan any Terms of Service page
  • View risk scores, flagged clauses, and full extraction
  • Access your scan history and account settings

Go to themys.ca/scan/new to start a scan.

Extension Permissions Explained

The extension requests four permissions:

PermissionPurpose --------------------- activeTabReads the content of your current tab to extract Terms of Service text. Only accesses the tab you're actively viewing. storageSaves your authentication token locally so you stay signed in between sessions. tabsEnables communication between the popup UI and the content script that runs on the page. alarmsKeeps the service worker alive on Manifest V3. Without this, Chrome would terminate the background process.

Themys does not request access to your browsing history, bookmarks, or any tab you aren't actively using.

Verifying the Installation

After installing, verify everything works:

1. Click the Themys icon in your Chrome toolbar

2. You should see the popup with a sign-in prompt (or your account info if already signed in)

3. Navigate to any Terms of Service page (e.g., github.com/terms)

4. The extension should detect the ToS content and display an overlay

If the extension doesn't activate:

  • Check that the extension is enabled at chrome://extensions
  • Verify you're on a page that contains Terms of Service content
  • Try clicking the extension icon manually to trigger a scan
  • Check the browser console for errors (F12 > Console tab)

Updating the Extension

Chrome Web Store

Updates are automatic. Chrome checks for extension updates periodically. To force a check:

1. Go to chrome://extensions

2. Enable Developer mode

3. Click Update

Unpacked (Development)

After pulling new changes:

bash
pnpm install          # if dependencies changed

pnpm build:extension  # rebuild

Then click the refresh icon on the Themys extension card at chrome://extensions.

Uninstalling

1. Right-click the Themys icon in your toolbar

2. Select Remove from Chrome

3. Confirm the removal

This removes the extension and its local storage. Your account and scan history remain on the server. Log in at themys.ca to manage or delete your data.

Troubleshooting

Extension icon is grayed out

The extension only activates on pages it can read. If the icon is grayed out:

  • You're on a Chrome internal page (chrome://...)
  • You're on the Chrome Web Store
  • The page hasn't fully loaded yet

"Cannot access contents of the page" error

This happens when the extension tries to read a restricted page:

  • Chrome settings pages (chrome://settings)
  • The Chrome Web Store (chromewebstore.google.com)
  • New Tab page

Navigate to a regular website and try again.

Extension popup doesn't open

1. Check if the extension is enabled at chrome://extensions

2. Disable and re-enable the extension

3. If that doesn't work, remove the extension and load it again

4. Check the Chrome DevTools console for the popup: right-click the popup > Inspect

Content script not injecting

If the extension loads but doesn't detect ToS content:

1. Open DevTools on the page (F12)

2. Go to the Console tab

3. Look for errors mentioning themys or content-script

4. Check if the page has a Content Security Policy that blocks inline scripts

Multiple Chrome profiles

The extension is installed per-Chrome-profile. If you use multiple Chrome profiles:

  • Install the extension in each profile where you want to use it
  • Each profile has its own extension state and login session
  • Switching profiles doesn't affect the extension in other profiles

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