changedetection

name	changedetection
description	Monitor websites for changes using changedetection.io. Create watches for price tracking, stock alerts, and content monitoring. Use for price monitoring, wishlist tracking, or any website change detection.
allowed-tools	Bash(curl:*)

Website Monitoring with ChangeDetection.io

Monitor websites for price changes, stock availability, and content updates. Requires $CHANGEDETECTION_URL and $CHANGEDETECTION_API_KEY environment variables. If not configured, tell the user to run /add-changedetection on the host to set it up.

Authentication

All requests use the x-api-key header:

curl -s "${CHANGEDETECTION_URL}/api/v1/watch" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

Creating a Watch

Basic watch

curl -s -X POST "${CHANGEDETECTION_URL}/api/v1/watch" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com/product-page",
    "title": "Product Name - Price Watch"
  }'

Price monitoring watch (with webhook notification)

curl -s -X POST "${CHANGEDETECTION_URL}/api/v1/watch" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com/product-page",
    "title": "Product Name - Price Watch",
    "include_filters": [".price", ".product-price", "[data-price]"],
    "processor": "restock_diff",
    "track_ldjson_price_data": true,
    "time_between_check": {"hours": 4},
    "notification_urls": ["json://'"${NANOCLAW_WEBHOOK_URL}"'"],
    "notification_title": "Price Change: {watch_title}",
    "notification_body": "{watch_url} changed. Check the latest snapshot.",
    "notification_format": "text"
  }'

Watch with CSS selector for specific element

curl -s -X POST "${CHANGEDETECTION_URL}/api/v1/watch" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://example.com/product",
    "title": "Descriptive title",
    "include_filters": ["div.price-container", "span.current-price"],
    "subtractive_selectors": ["div.ads", "nav", "footer"],
    "time_between_check": {"hours": 6}
  }'

Webhook Notification Setup

To have changedetection.io notify NanoClaw when a change is detected, use the notification_urls field with the NanoClaw webhook:

json://NANOCLAW_HOST:3457/webhook

The NANOCLAW_WEBHOOK_URL env var contains the full webhook URL if configured. The notification will be POSTed as JSON to NanoClaw's webhook endpoint.

Important: The webhook needs the Bearer token. When setting up notifications, use this format:

json://NANOCLAW_HOST:3457/webhook?+HeaderName=Authorization&-Authorization=Bearer+WEBHOOK_SECRET

Or configure the notification in changedetection.io's global settings UI to include the Authorization header.

Listing Watches

# List all watches (returns UUID-keyed dictionary)
curl -s "${CHANGEDETECTION_URL}/api/v1/watch" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}" | python3 -c "
import sys, json
watches = json.load(sys.stdin)
for uuid, w in watches.items():
    title = w.get('title', 'Untitled')
    url = w.get('url', '')
    last = w.get('last_changed', 'never')
    print(f'{title}: {url} (last changed: {last}, uuid: {uuid})')
"

Getting Watch Details

curl -s "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

Getting Latest Snapshot

# Get history timestamps
curl -s "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID/history" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

# Get latest snapshot content
curl -s "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID/history/latest" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

Comparing Changes

# Compare previous vs latest snapshot
curl -s "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID/difference/previous/latest?format=text" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

Updating a Watch

curl -s -X PUT "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}" \
  -H "Content-Type: application/json" \
  -d '{
    "time_between_check": {"hours": 1},
    "include_filters": [".new-price-selector"]
  }'

Deleting a Watch

curl -s -X DELETE "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

Trigger Immediate Recheck

curl -s "${CHANGEDETECTION_URL}/api/v1/watch/WATCH_UUID?recheck=1" \
  -H "x-api-key: ${CHANGEDETECTION_API_KEY}"

Price Monitoring Workflow

When monitoring prices from a Notion wishlist:

1. Read the wishlist from Notion (use the notion skill)
2. For each product URL, create a watch with:
   • include_filters targeting the price element (inspect the page to find the right CSS selector)
   • processor: "restock_diff" for e-commerce pages
   • track_ldjson_price_data: true to extract structured price data from JSON-LD
   • notification_urls pointing to NanoClaw's webhook
   • time_between_check set to a reasonable interval (4-12 hours for prices)
3. When a price changes, the webhook fires, and you can:
   • Fetch the diff to see old vs new price
   • Notify the user with the price change details
   • Update the Notion wishlist with the new price

Common CSS Selectors for Prices

• Amazon: .a-price .a-offscreen, #priceblock_ourprice
• eBay: .x-price-primary span
• Generic: .price, [data-price], .product-price
• JSON-LD: Enable track_ldjson_price_data instead of CSS selectors

Tip: If unsure about the selector, create the watch without include_filters first. Check the snapshot to see what content is captured, then refine with specific selectors.

Troubleshooting

• Watch not detecting changes: The CSS selector might be wrong. Check the latest snapshot content to verify what's being captured.
• Notification not firing: Verify the webhook URL is correct and reachable from the changedetection.io host.
• JavaScript-rendered content: Set fetch_backend to "html_webdriver" for pages that require JavaScript rendering (requires Playwright/browser setup in changedetection.io).