# Website Change Monitor & Alerter (`second_coming/website-change-monitor`) Actor

Monitor web pages for content changes. Track page diffs, get webhook alerts when monitored pages change. Supports CSS selectors for targeting specific sections.

- **URL**: https://apify.com/second\_coming/website-change-monitor.md
- **Developed by:** [Richard P](https://apify.com/second_coming) (community)
- **Categories:** Developer tools, AI
- **Stats:** 2 total users, 1 monthly users, 0.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

Pay per usage

This Actor is paid per platform usage. The Actor is free to use, and you only pay for the Apify platform usage, which gets cheaper the higher subscription plan you have.

Learn more: https://docs.apify.com/platform/actors/running/actors-in-store#pay-per-usage

## What's an Apify Actor?

Actors are web data automations that power AI and operations. They run on the Apify platform to scrape websites, process data, connect APIs, and automate workflows.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.
Actors are written with capital "A".

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.
The best way to integrate Actors is as follows.

- **AI agents and MCP clients** — the [Apify MCP server](https://docs.apify.com/integrations/mcp.md) at `https://mcp.apify.com` (remote, streamable HTTP, OAuth on first use).
- **Agentic workflows and local Actor development** — [Agent Skills](https://apify.com/.well-known/agent-skills/index.json) with the [Apify CLI](https://docs.apify.com/cli/docs.md): `npm install -g apify-cli`, then `apify login`.
- **JavaScript/TypeScript projects** — the official [JS/TS client](https://docs.apify.com/api/client/js/docs.md): `npm install apify-client`.
- **Python projects** — the official [Python client](https://docs.apify.com/api/client/python/docs.md): `pip install apify-client`.
- **Any other language** — the [REST API](https://docs.apify.com/api/v2.md).

For usage examples, see the [API](#api) section below.

For more details, see Apify documentation as [Markdown index](https://docs.apify.com/llms.txt) and [Markdown full-text](https://docs.apify.com/llms-full.txt).

# README

## Website Change Monitor & Alerter

Monitor web pages for content changes and get alerted when something changes.

### How it works

1. Provide a list of URLs to watch
2. The Actor fetches each page and computes a content fingerprint (SHA-256 hash)
3. On each run, it compares against the previously stored fingerprint
4. If content changed: it generates a diff, records the change event, and optionally sends a webhook alert
5. If unchanged: quietly records the check (in "all\_runs" mode) or skips (in "changes\_only" mode)

### Features

- **CSS Selector Support** — monitor only a specific part of a page (e.g., `#pricing-table`, `.announcement-bar`)
- **Smart Diffing** — generates unified diffs showing exactly what changed
- **Webhook Alerts** — POST change notifications to any HTTP endpoint
- **Persistent State** — fingerprints are stored in Apify's key-value store between runs
- **Schedule-Friendly** — designed for cron/scheduled runs; only alerts on actual changes

### Input

| Field | Type | Description |
|-------|------|-------------|
| `urls` | array | List of URL objects to monitor |
| `urls[].url` | string | **Required.** The page URL |
| `urls[].name` | string | Optional label for the page |
| `urls[].selector` | string | Optional CSS selector to watch a specific section |
| `webhookUrl` | string | URL to POST change notifications to |
| `notificationType` | enum | `"changes_only"` (default) or `"all_runs"` |

### Webhook Payload

When a change is detected, a POST request with JSON body is sent to your webhook URL:

```json
{
  "event": "page_changed",
  "name": "My Page",
  "url": "https://example.com",
  "changed_at": "2024-01-01T00:00:00+00:00",
  "diff_preview": "--- previous\n+++ current\n@@ -1 +1 @@\n-old content\n+new content",
  "previous_hash": "abc...",
  "current_hash": "def..."
}
```

### Use Cases

- Monitor competitor website changes (pricing, features, copy)
- Track documentation, terms of service, or policy updates
- Watch job postings for new openings
- Monitor regulatory or compliance page changes
- Detect when a product goes in/out of stock

# Actor input Schema

## `urls` (type: `array`):

List of web pages to monitor for changes. Each entry can optionally include a CSS selector to watch only a specific part of the page.

## `webhookUrl` (type: `string`):

Optional URL to POST change notifications to. The webhook will receive a JSON payload with change details when a page changes.

## `notificationType` (type: `string`):

When to send webhook notifications: 'changes\_only' (default) sends alerts only when a change is detected. 'all\_runs' sends a summary after every run.

## Actor input object example

```json
{
  "urls": [
    {
      "url": "https://example.com",
      "name": "Example Homepage",
      "selector": ""
    }
  ],
  "notificationType": "changes_only"
}
```

# Actor output Schema

## `results` (type: `string`):

No description

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "urls": [
        {
            "url": "https://example.com",
            "name": "Example Homepage",
            "selector": ""
        }
    ],
    "webhookUrl": ""
};

// Run the Actor and wait for it to finish
const run = await client.actor("second_coming/website-change-monitor").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = {
    "urls": [{
            "url": "https://example.com",
            "name": "Example Homepage",
            "selector": "",
        }],
    "webhookUrl": "",
}

# Run the Actor and wait for it to finish
run = client.actor("second_coming/website-change-monitor").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print("💾 Check your data here: https://console.apify.com/storage/datasets/" + run["defaultDatasetId"])
for item in client.dataset(run["defaultDatasetId"]).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "urls": [
    {
      "url": "https://example.com",
      "name": "Example Homepage",
      "selector": ""
    }
  ],
  "webhookUrl": ""
}' |
apify call second_coming/website-change-monitor --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "command": "npx",
            "args": [
                "mcp-remote",
                "https://mcp.apify.com/?tools=second_coming/website-change-monitor",
                "--header",
                "Authorization: Bearer <YOUR_API_TOKEN>"
            ]
        }
    }
}

```

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/gUqFVlDvzOqTo5hpg/builds/6xczHzccqxHgDfUSq/openapi.json