# URL Content Change Monitor (`engineertsaistudio/url-content-change-monitor`) Actor

Fetches a URL, hashes a selected text region (or full page), and reports whether content changed since the last check. Pay-per-event: charges the buyer only when a real change is detected, not per poll.

- **URL**: https://apify.com/engineertsaistudio/url-content-change-monitor.md
- **Developed by:** [Studio EngineerTsai](https://apify.com/engineertsaistudio) (community)
- **Categories:**
- **Stats:** 1 total users, 0 monthly users, 0.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $50.00 / 1,000 content 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?

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

## URL Content Change Monitor — Apify Actor (pay-per-event)

Fetches a URL, hashes a selected region (or the full page text), and compares against the last stored hash for the same `monitorKey`. Reports whether the content changed since the last run.

Built from real, evidenced demand: `CHANGE_MONITORING` ranked #2 in AG's 2026-08-30 demand graph (25 cross-source signals across 9 independent sources — Stack Exchange + GitHub Issues; see `research/DEMAND_GRAPH_CLUSTERS_2026-08-30.json`). Apify's and RapidAPI's own current documented pricing patterns both explicitly name monitoring/alerting as a real, established paid category.

### Input

- `url` (required) — page to check
- `monitorKey` (required) — stable identifier so repeated runs compare against the same stored state (e.g. `"vendor-x-pricing-page"`)
- `cssSelector` (optional) — an `#id` or `.class` selector to narrow what's hashed; anything else (including tag selectors like `h1`) falls back to hashing the full page text, by design — this Actor is a deterministic diff tool, not a full CSS engine

### Pricing (pay-per-event)

- `actor-start`: $0.01 — every run
- `change-detected`: $0.05 — **only** when the content actually changed

The buyer pays for signal, not for polling — a genuine differentiation from a plain scheduled scraper.

### Real local verification (done, not just written)

Tested against the real, installed `apify` Python SDK v4.0.1, using `APIFY_LOCAL_STORAGE_DIR` and `ACTOR_TEST_PAY_PER_EVENT=1`. Three real states verified in sequence against `https://example.com`:

1. First run: `first_run: true, changed: false` (no prior state)
2. Second run, unchanged page: `first_run: false, changed: false`
3. Simulated prior state with a different hash: `first_run: false, changed: true`

**Real bug caught and fixed during this testing**: `Actor.open_key_value_store()` with no name argument creates a fresh, randomly-identified store on every local run (state never persisted across runs). Fixed by using a named store (`open_key_value_store(name="change-monitor-state")`), which correctly round-trips state across separate process invocations. This is recorded here so the fix isn't silently lost.

### Deployed and public

Real, published, public Apify Actor: https://apify.com/engineertsaistudio/url-content-change-monitor (Actor ID `8cnpaMoEUpNOgH8gN`). Build 0.0.1 succeeded on the first attempt, real test run against `https://example.com` succeeded with correct output. Pay-per-event monetization configured live in the Console's Publishing > Monetization wizard, matching this README's pricing table. Payout/KYC completeness for real payouts is tracked separately and not implied by publication alone.

# Actor input Schema

## `url` (type: `string`):

The page to fetch and check for changes.

## `cssSelector` (type: `string`):

If set, only this element's text is hashed. If empty, the full page text is hashed.

## `monitorKey` (type: `string`):

A stable identifier for this monitor so repeated runs compare against the same stored hash (e.g. 'vendor-x-pricing-page').

## Actor input object example

```json
{}
```

# 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 = {};

// Run the Actor and wait for it to finish
const run = await client.actor("engineertsaistudio/url-content-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 = {}

# Run the Actor and wait for it to finish
run = client.actor("engineertsaistudio/url-content-change-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 '{}' |
apify call engineertsaistudio/url-content-change-monitor --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,engineertsaistudio/url-content-change-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/8cnpaMoEUpNOgH8gN/builds/Je8P7Kniw9582rD9D/openapi.json