# Website Monitor - Change Detection for Any Page (`aolmo/website-monitor`) Actor

Checks web pages on a schedule and reports exactly what changed: text, title, description, prices, links and images. Plain HTTP, no browser, no proxies: fast and cheap.

- **URL**: https://apify.com/aolmo/website-monitor.md
- **Developed by:** [Antonio del Olmo Tena](https://apify.com/aolmo) (community)
- **Categories:** Automation, Developer tools
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $10.00 / 1,000 change detecteds

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

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

## What's an Apify Actor?

An Actor is a serverless cloud program that runs on the Apify platform. It has two run modes.
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.

Apify vocabulary and the platform model are defined once, in the agent quickstart at https://apify.com/agents.md.

## 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.

Do not guess an integration path. Every one of them is in the agent quickstart at https://apify.com/agents.md: the Apify MCP server, Agent Skills with the Apify CLI, the JavaScript and Python clients, the REST API, and the account-free path for an agent with no human to sign in. It also carries the rule on stating cost before the first paid run.

For examples already wired to this Actor's own input schema, see the [API](#api) section below.

Each client library has reference documentation the quickstart does not restate: [JavaScript/TypeScript](https://docs.apify.com/api/client/js/docs.md) (`npm install apify-client`) and [Python](https://docs.apify.com/api/client/python/docs.md) (`pip install apify-client`).

# README

Website Monitor checks a list of web pages and reports **exactly what changed since the previous run**: visible text, title, meta description, prices, links and images. It works with a plain HTTP request, no browser, no proxies and no CAPTCHA bypass, so it is fast, cheap and easy to schedule.

Typical uses: price tracking on product pages, watching competitor sites, detecting new links or documents on a page, monitoring "pricing", "jobs" or "news" pages, and checking that a page you depend on still looks the way you expect.

### What you get

For every URL you give it, the Actor returns one Dataset item with:

- `changed`: `true` when something you asked to watch changed since the previous run.
- `events`: a list of what changed, such as `PRICE_CHANGED`, `TITLE_CHANGED`, `TEXT_CHANGED`, `DESCRIPTION_CHANGED`, `LINK_ADDED`, `LINK_REMOVED`, `IMAGE_ADDED`, `IMAGE_REMOVED`, each with details (old and new value, or the URL that appeared or disappeared).
- `data`: the normalized content of the page: title, description, text, prices, links, images and one hash per element.

Pages that fail (blocked host, HTTP error, timeout) are returned with an `error` field instead of failing the whole run.

### How to use it

1. Open the Actor and go to the **Input** tab.
2. In **Targets**, add one object per page: `{ "url": "https://example.org/pricing", "detect": ["price", "text"] }`. `detect` is optional; leave it out to watch everything.
3. Click **Start**. The first run only stores the baseline, so `changed` is `false` for every page.
4. Click **Start** again whenever you want to check, or better, schedule it: open the run, click **Create schedule** and pick hourly, daily or weekly. Every run compares each page with the previous snapshot.
5. Read the results in the **Output** tab, download them as JSON or CSV, or connect an integration (webhook, Slack, email) so you are notified when `changed` is `true`.

### Input

```json
{
  "targets": [
    { "url": "https://books.toscrape.com/", "detect": ["price", "links"] },
    { "url": "https://example.org/pricing" }
  ]
}
```

| Field               | Description |
|---------------------|-------------|
| `targets[].url`     | Public http(s) URL. Private or internal addresses are rejected. |
| `targets[].detect`  | Optional. Any of `text`, `title`, `description`, `price`, `links`, `images`. Default: all. |
| `product`           | Advanced. Adapter to run; leave `website-monitor`. |

Up to 50 targets per run.

### Output example

```json
{
  "url": "https://books.toscrape.com/",
  "product": "website",
  "changed": true,
  "events": [
    { "type": "PRICE_CHANGED", "data": { "from": [{ "value": 51.77, "currency": "GBP" }], "to": [{ "value": 49.99, "currency": "GBP" }] } },
    { "type": "LINK_ADDED", "data": { "url": "https://books.toscrape.com/catalogue/new-book_2000/index.html" } }
  ],
  "data": {
    "title": "All products | Books to Scrape - Sandbox",
    "description": "",
    "text": "Books to Scrape We love being scraped! ...",
    "prices": [{ "value": 49.99, "currency": "GBP", "raw": "£49.99" }],
    "links": ["https://books.toscrape.com/catalogue/..."],
    "images": ["https://books.toscrape.com/media/..."],
    "hashes": { "titleHash": "...", "textHash": "...", "pricesHash": "...", "linksHash": "...", "imagesHash": "..." }
  },
  "timestamp": "2026-10-01T16:06:24.277Z"
}
```

### How change detection works

Each page is cleaned (scripts, styles, comments and dynamic attributes removed), normalized and hashed element by element. The snapshot is stored in a Key-Value Store in your account, so the next run, scheduled or manual, compares against it. Only the fields listed in `detect` are compared: a page with a changing footer can still be watched for price changes only.

### Pricing

You pay per event, nothing else:

- **URL checked** ($0.002): one page fetched, normalized and compared with its previous snapshot.
- **Change detected** ($0.01): the page changed since the previous run; the item lists exactly what changed.
- **Actor start** ($0.00005): Apify's standard start fee.

Targets that fail are never charged. Example: 20 URLs checked every hour for a month cost about $29, plus $0.01 per detected change. You can cap the spend of every run with the "Maximum total charge" option; when the cap is reached the remaining targets are returned with an error instead of being checked.

### Use it as an API

Every Actor can be called over HTTP. This request runs the check and returns the Dataset items in one call:

```bash
curl -X POST "https://api.apify.com/v2/acts/USERNAME~website-monitor/run-sync-get-dataset-items?token=YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"targets":[{"url":"https://books.toscrape.com/","detect":["price"]}]}'
```

Replace `USERNAME~website-monitor` with the Actor ID shown on this page. For large batches use the asynchronous `/runs` endpoint and read the Dataset when the run finishes.

### FAQ

**Why is `changed` false on the first run?** There is no previous snapshot yet. The first run stores the baseline; from the second run on, differences are reported.

**Does it work with pages rendered by JavaScript?** It reads the HTML the server sends. Pages that render only in the browser will expose their initial HTML, which may be empty.

**`text` changes on every run. What can I do?** Some pages show dates or counters that change on each visit. Narrow `detect` to the fields you care about, for example `["price", "links"]`.

**Which currencies are recognized?** Prices are read from visible text (`19,99 €`, `$1,234.56`, `EUR 5`) and from JSON-LD `offers`, with EUR, USD, GBP, JPY, CHF, MXN and BRL.

**Is anything bypassed?** No. The Actor does not evade CAPTCHAs, WAFs or anti-bot systems, and it never requests private or internal addresses.

# Actor input Schema

## `product` (type: `string`):

Product adapter to run. Currently: website-monitor.

## `targets` (type: `array`):

Pages to monitor. Each item: { "url": "https://...", "detect": \["text", "title", "description", "price", "links", "images"] }. "detect" is optional (defaults to all).

## Actor input object example

```json
{
  "product": "website-monitor",
  "targets": [
    {
      "url": "https://books.toscrape.com/",
      "detect": [
        "text",
        "price",
        "links"
      ]
    }
  ]
}
```

# Actor output Schema

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

Dataset items: url, changed, events, data, timestamp and error (when the target failed).

# 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 = {
    "targets": [
        {
            "url": "https://books.toscrape.com/",
            "detect": [
                "text",
                "price",
                "links"
            ]
        }
    ]
};

// Run the Actor and wait for it to finish
const run = await client.actor("aolmo/website-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 = { "targets": [{
            "url": "https://books.toscrape.com/",
            "detect": [
                "text",
                "price",
                "links",
            ],
        }] }

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

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

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

```

## CLI example

```bash
echo '{
  "targets": [
    {
      "url": "https://books.toscrape.com/",
      "detect": [
        "text",
        "price",
        "links"
      ]
    }
  ]
}' |
apify call aolmo/website-monitor --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,aolmo/website-monitor"
        }
    }
}
```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/W8YJsX8m8cWLmYdSU/builds/Y5Bwmu1e9ewgYPPIg/openapi.json