# Page Watch — Website Change Monitor & Content Tracker (`mfapitools/page-watch`) Actor Monitor any URL for content changes with hash-based change detection. Pay per check + per detected change. Ideal for watching competitor pages, docs, pricing, or any public web page. - **URL**: https://apify.com/mfapitools/page-watch.md - **Developed by:** [Mariano Ferreras](https://apify.com/mfapitools) (community) - **Categories:** Automation, Developer tools, SEO tools - **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks - **User rating**: No ratings yet ## Pricing from $1.00 / 1,000 page checkeds 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/platform/actors/running/actors-in-store#pay-per-event ## What's an Apify Actor? Actors are a software tools running on the Apify platform, for all kinds of web data extraction and automation use cases. 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. In JavaScript/TypeScript projects, use official [JavaScript/TypeScript client](https://docs.apify.com/api/client/js/docs.md): ```bash npm install apify-client ``` In Python projects, use official [Python client library](https://docs.apify.com/api/client/python/docs.md): ```bash pip install apify-client ``` In shell scripts, use [Apify CLI](https://docs.apify.com/cli/docs.md): ````bash # MacOS / Linux curl -fsSL https://apify.com/install-cli.sh | bash # Windows irm https://apify.com/install-cli.ps1 | iex ```bash In AI frameworks, you might use the [Apify MCP server](https://docs.apify.com/integrations/mcp.md). If your project is in a different language, use 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 ## Page Watch — Website Change Monitor > **Pay-per-event pricing.** Fetches URLs, hashes their content, and compares against the previous run's hash stored in Apify's KeyValueStore. Per-URL CSS selectors scope the check to specific page sections. A noise threshold (`minChangeRatio`) suppresses small changes from rotating widgets or ad slots. Several competitors offer similar features — this is a commodity market; pick based on price and reliability. $0.001/check + $0.01/change. The most important limitation: ultimate page-watch is trivial to DIY — a cron job + `curl | sha256sum`. You're paying for the hosted scheduler, KVS persistence across runs, and the CSS-selector noise-threshold UX. --- ### What it does This actor fetches one or more URLs, extracts the page text (optionally scoped to specific sections via CSS selectors), computes a content hash, and compares it against the previous check's hash stored in the actor's persistent KeyValueStore. An optional noise threshold (`minChangeRatio`, using Dice coefficient over word multisets) ignores small content churn so you only get charged for changes that matter. Each result includes the hashes and a diff excerpt around the first divergence. Several competitors offer similar features (e.g. `foo121/website-change-monitor` has CSS selectors + noise-filtered diffing, `ryanclinton/website-change-monitor` has 31 users). Run it once to establish a baseline, then schedule it (e.g. every hour, daily) to **monitor web pages** continuously. Because it uses Apify's built-in KeyValueStore, the hash state persists across scheduled runs — no external storage needed. If you're doing **competitor page tracking** at scale, batch multiple URLs into a single run to work around Apify's schedule limit (100 per account). --- ### Use cases - **Competitor page tracking** — watch competitor landing pages, product pages, or docs for changes. Get notified when they update pricing, features, or copy. - **Price tracking** — watch pricing pages on e-commerce or SaaS sites. Detects when prices go up or down. - **Documentation change alerts** — monitor API docs, terms of service, or compliance pages. Know the moment something changes. - **Regulatory / legal monitoring** — watch government pages, procurement portals, or regulatory sites for new announcements. - **Agent-powered watchlists** — wire this into an AI agent workflow: have your agent set up monitors, check diff excerpts, and summarize what changed. --- ### Input example Watch only a price div on one page, the full body on another, and ignore under-2% churn everywhere: ```json { "urls": [ { "url": "https://example.com/pricing", "selector": ".pricing-table" }, "https://example.com/docs" ], "minChangeRatio": 0.02, "maxItems": 50, "useResidentialProxy": false } ```` | Field | Type | Default | Description | |---|---|---|---| | `urls` | array | required | One or more URLs to check. Each entry can be a plain URL string, `{ "url": "..." }`, or `{ "url": "...", "selector": "..." }` to scope just that URL to a CSS selector | | `defaultSelector` | string | none | CSS selector applied to any URL that doesn't set its own `selector`. Example: `.pricing-table` | | `minChangeRatio` | number | `0` | Noise threshold in `[0, 1]`. `0` (default) reports every content hash difference, same as before. `0.02` ignores under-2% content churn — the hash still notices the diff, but it won't be reported as `changed` or charged unless the changed fraction meets the threshold | | `selectors` | array | `[]` | Legacy, global multi-selector mode — applied only to URLs with no per-URL `selector` and no `defaultSelector`. Kept for backward compatibility | | `maxItems` | integer | `50` | Max URLs to check in this run. `0` = unlimited | | `useResidentialProxy` | boolean | `false` | Upgrade to residential proxies if the target blocks datacenter IPs | #### Per-URL selectors — behavior - Selector resolution order per URL: its own `selector` → `defaultSelector` → the legacy global `selectors` array → full page body. - **A bad selector never produces a silent phantom "change".** If a per-URL/default selector is invalid CSS or matches no content on the page, the actor logs a warning, sets `selectorWarning` on that URL's result row, and falls back to hashing the full page instead of a stable empty string. - Switching a URL's selector (adding, removing, or changing it) changes what's being tracked, so the very next check may legitimately report one change as the new baseline is established — this is expected, not a bug. *** ### Output example ```json [ { "url": "https://example.com/pricing", "checkedAt": "2026-07-23T23:00:00.000Z", "changed": true, "hash": "a1b2c3d4e5f6g7h8", "previousHash": "9i8j7k6l5m4n3o2p", "title": "Example — Pricing", "contentLength": 4523, "selector": ".pricing-table", "selectorWarning": null, "diffSnippetPrevious": "...our starter plan is $10 per month with...", "diffSnippetCurrent": "...our starter plan is $15 per month with...", "changeRatio": 0.18, "belowChangeThreshold": false } ] ``` | Field | Type | Notes | |---|---|---| | `url` | string | The URL that was checked | | `checkedAt` | string | ISO 8601 timestamp of the check | | `changed` | boolean | `true` only when the content hash differs from the previous check AND (if `minChangeRatio` is set) the changed fraction meets the threshold | | `hash` | string | SHA-256 hex digest (first 16 chars) of the current extracted content | | `previousHash` | string|null | Hash from the previous check. `null` on the first run | | `title` | string|null | Page `` content | | `contentLength` | integer | Character count of the extracted text | | `selector` | string|null | CSS selector actually used to extract content (per-URL, `defaultSelector`, or the legacy `selectors` list joined). `null` for full-page checks | | `selectorWarning` | string|null | Set when a per-URL/default selector was invalid or matched nothing — the check fell back to full-page text. `null` when no issue occurred | | `diffSnippetPrevious` | string|null | Excerpt of the previous content around the first difference. `null` when unchanged or first check | | `diffSnippetCurrent` | string|null | Excerpt of the current content around the first difference. `null` when unchanged or first check | | `changeRatio` | number|null | Fraction of content changed vs. the previous check (`0`-`1`), computed only when the hash differs and a previous check exists. `null` otherwise | | `belowChangeThreshold` | boolean | `true` when the hash differed but `changeRatio` was below `minChangeRatio` — a real change was detected but suppressed as noise (not reported, not charged) | *** ### Pricing This actor uses **pay-per-event** pricing. You are never charged for failed requests or quarantined results. | Event | Price | Description | |---|---|---| | `page-checked` | $1.00 / 1,000 checks | Charged once per URL checked, regardless of whether it changed | | `page-changed` | $10.00 / 1,000 changes | Charged once per detected change (in addition to the check fee) | The `page-changed` event is only triggered when content actually differs from the previous check. Use a small `maxItems` for test runs. At $0.001/check, monitoring 10 URLs daily costs ~$0.30/month. *** ### Scheduling Page Watch is designed to be run on a schedule. Create a schedule in Apify Console (e.g. hourly, daily) and the actor will automatically compare against the previous run's hashes stored in its KeyValueStore. To watch multiple URLs, batch them into a single run using the `urls` input array. This works around Apify's schedule limit (100 per account) and is more efficient than one schedule per URL. *** ### Use with AI agents (MCP) This actor is available as a tool for AI assistants via the Apify MCP server. Agents can call it to **monitor web pages for content changes** directly — no Apify console needed, just a single function call. #### MCP setup ```json { "mcpServers": { "apify": { "command": "npx", "args": [ "mcp-remote", "https://mcp.apify.com?tools=mfapitools/page-watch", "--header", "Authorization: Bearer <YOUR_API_TOKEN>" ] } } } ``` #### Example agent prompts - "Monitor these five competitor pricing pages and tell me if any changed" - "Set up change detection for this government procurement portal URL" - "Check all my watched URLs and summarize the diffs" The actor returns structured JSON with the same fields shown above. Agentic workflows (Claude Code, Cursor, any MCP-compatible AI) can monitor pages and analyze change excerpts in the same run. *** ### Limitations - **Text-based comparison** — the actor extracts normalized body text (with `<script>`, `<style>`, `<noscript>` stripped to avoid false positives from inline nonces/timestamps) and computes a hash. On change, you get a small excerpt around the *first* divergence — not a full structural or visual diff, and not an LLM "what changed" summary (planned for a future version). - **First run is always a baseline** — the first check of any URL will show `changed: false` because there is no previous hash. The second run detects changes. - **`minChangeRatio` compares only the first ~10,000 characters** of extracted text from each side (the same window used for diff-snippet storage) — a size-bounded, cheap comparison. For most pages this is representative of the whole page; for very large pages, changes past that window won't move the ratio. - **Public data only** — this actor fetches public URLs. No login-gated content. - **No notification delivery in v1.0** — changes are recorded in the dataset. You can wire up webhooks or Apify's email/slack integrations in Console to get notified when new results arrive. - **Hash collisions are theoretically possible** — using SHA-256 truncated to 16 hex chars (64 bits). The collision probability is negligible for this use case (~2^-32 for 100k checks). *** ### Changelog See [CHANGELOG.md](./CHANGELOG.md). # Actor input Schema ## `urls` (type: `array`): One or more URLs to check for content changes. Each URL is fetched, hashed, and compared against its previous hash (stored in the actor's KeyValueStore). Accepts plain strings, { "url": "..." } objects, or { "url": "...", "selector": "..." } to scope just that URL to a CSS selector (e.g. watch only a price div on one page while monitoring the full body on another). A bad/no-match selector falls back to full-page text with a loud warning — it never silently reports a phantom change. ## `defaultSelector` (type: `string`): Fallback CSS selector applied to any URL in the list that doesn't set its own per-URL selector. Example: ".pricing-table". Leave empty to use the legacy `selectors` field (or full page) instead. ## `selectors` (type: `array`): Deprecated in favor of per-URL { url, selector } entries or `defaultSelector` — kept for backward compatibility. Applied only to URLs that have no per-URL selector and no defaultSelector. If empty, the full page body text is monitored. Example: \[".pricing-table", ".product-description"] ## `minChangeRatio` (type: `number`): Ignore small changes. 0 (default) reports every content hash difference, same as before. Set e.g. 0.02 to only report/charge a change when at least 2% of the tracked text differs from the previous check — useful for pages with small rotating widgets, ad slots, or view counters that would otherwise trigger noisy false positives. ## `maxItems` (type: `integer`): Maximum number of URLs to check in this run. 0 = unlimited. You are charged per check and per detected change. ## `useResidentialProxy` (type: `boolean`): Switch to residential proxies if datacenter IPs are blocked. Increases cost but may be needed for bot-protected targets. ## Actor input object example ```json { "urls": [ { "url": "https://example.com" } ], "selectors": [], "minChangeRatio": 0, "maxItems": 50, "useResidentialProxy": false } ``` # 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" } ], "selectors": [] }; // Run the Actor and wait for it to finish const run = await client.actor("mfapitools/page-watch").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" }], "selectors": [], } # Run the Actor and wait for it to finish run = client.actor("mfapitools/page-watch").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" } ], "selectors": [] }' | apify call mfapitools/page-watch --silent --output-dataset ``` ## MCP server setup ```json { "mcpServers": { "apify": { "command": "npx", "args": [ "mcp-remote", "https://mcp.apify.com/?tools=mfapitools/page-watch", "--header", "Authorization: Bearer <YOUR_API_TOKEN>" ] } } } ``` ## OpenAPI specification ```json { "openapi": "3.0.1", "info": { "title": "Page Watch — Website Change Monitor & Content Tracker", "description": "Monitor any URL for content changes with hash-based change detection. Pay per check + per detected change. Ideal for watching competitor pages, docs, pricing, or any public web page.", "version": "0.1", "x-build-id": "p2dW8XuCXsX0iF9tm" }, "servers": [ { "url": "https://api.apify.com/v2" } ], "paths": { "/acts/mfapitools~page-watch/run-sync-get-dataset-items": { "post": { "operationId": "run-sync-get-dataset-items-mfapitools-page-watch", "x-openai-isConsequential": false, "summary": "Executes an Actor, waits for its completion, and returns Actor's dataset items in response.", "tags": [ "Run Actor" ], "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/inputSchema" } } } }, "parameters": [ { "name": "token", "in": "query", "required": true, "schema": { "type": "string" }, "description": "Enter your Apify token here" } ], "responses": { "200": { "description": "OK" } } } }, "/acts/mfapitools~page-watch/runs": { "post": { "operationId": "runs-sync-mfapitools-page-watch", "x-openai-isConsequential": false, "summary": "Executes an Actor and returns information about the initiated run in response.", "tags": [ "Run Actor" ], "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/inputSchema" } } } }, "parameters": [ { "name": "token", "in": "query", "required": true, "schema": { "type": "string" }, "description": "Enter your Apify token here" } ], "responses": { "200": { "description": "OK", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/runsResponseSchema" } } } } } } }, "/acts/mfapitools~page-watch/run-sync": { "post": { "operationId": "run-sync-mfapitools-page-watch", "x-openai-isConsequential": false, "summary": "Executes an Actor, waits for completion, and returns the OUTPUT from Key-value store in response.", "tags": [ "Run Actor" ], "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/inputSchema" } } } }, "parameters": [ { "name": "token", "in": "query", "required": true, "schema": { "type": "string" }, "description": "Enter your Apify token here" } ], "responses": { "200": { "description": "OK" } } } } }, "components": { "schemas": { "inputSchema": { "type": "object", "required": [ "urls" ], "properties": { "urls": { "title": "URLs to watch", "type": "array", "description": "One or more URLs to check for content changes. Each URL is fetched, hashed, and compared against its previous hash (stored in the actor's KeyValueStore). Accepts plain strings, { \"url\": \"...\" } objects, or { \"url\": \"...\", \"selector\": \"...\" } to scope just that URL to a CSS selector (e.g. watch only a price div on one page while monitoring the full body on another). A bad/no-match selector falls back to full-page text with a loud warning — it never silently reports a phantom change.", "items": { "type": "object", "required": [ "url" ], "properties": { "url": { "type": "string", "title": "URL of a web page", "format": "uri" } } } }, "defaultSelector": { "title": "Default CSS selector (optional)", "type": "string", "description": "Fallback CSS selector applied to any URL in the list that doesn't set its own per-URL selector. Example: \".pricing-table\". Leave empty to use the legacy `selectors` field (or full page) instead." }, "selectors": { "title": "Legacy CSS selectors (optional)", "type": "array", "description": "Deprecated in favor of per-URL { url, selector } entries or `defaultSelector` — kept for backward compatibility. Applied only to URLs that have no per-URL selector and no defaultSelector. If empty, the full page body text is monitored. Example: [\".pricing-table\", \".product-description\"]" }, "minChangeRatio": { "title": "Minimum change ratio (noise threshold)", "minimum": 0, "maximum": 1, "type": "number", "description": "Ignore small changes. 0 (default) reports every content hash difference, same as before. Set e.g. 0.02 to only report/charge a change when at least 2% of the tracked text differs from the previous check — useful for pages with small rotating widgets, ad slots, or view counters that would otherwise trigger noisy false positives.", "default": 0 }, "maxItems": { "title": "Max URLs to check", "minimum": 0, "maximum": 100000, "type": "integer", "description": "Maximum number of URLs to check in this run. 0 = unlimited. You are charged per check and per detected change.", "default": 50 }, "useResidentialProxy": { "title": "Use residential proxies", "type": "boolean", "description": "Switch to residential proxies if datacenter IPs are blocked. Increases cost but may be needed for bot-protected targets.", "default": false } } }, "runsResponseSchema": { "type": "object", "properties": { "data": { "type": "object", "properties": { "id": { "type": "string" }, "actId": { "type": "string" }, "userId": { "type": "string" }, "startedAt": { "type": "string", "format": "date-time", "example": "2025-01-08T00:00:00.000Z" }, "finishedAt": { "type": "string", "format": "date-time", "example": "2025-01-08T00:00:00.000Z" }, "status": { "type": "string", "example": "READY" }, "meta": { "type": "object", "properties": { "origin": { "type": "string", "example": "API" }, "userAgent": { "type": "string" } } }, "stats": { "type": "object", "properties": { "inputBodyLen": { "type": "integer", "example": 2000 }, "rebootCount": { "type": "integer", "example": 0 }, "restartCount": { "type": "integer", "example": 0 }, "resurrectCount": { "type": "integer", "example": 0 }, "computeUnits": { "type": "integer", "example": 0 } } }, "options": { "type": "object", "properties": { "build": { "type": "string", "example": "latest" }, "timeoutSecs": { "type": "integer", "example": 300 }, "memoryMbytes": { "type": "integer", "example": 1024 }, "diskMbytes": { "type": "integer", "example": 2048 } } }, "buildId": { "type": "string" }, "defaultKeyValueStoreId": { "type": "string" }, "defaultDatasetId": { "type": "string" }, "defaultRequestQueueId": { "type": "string" }, "buildNumber": { "type": "string", "example": "1.0.0" }, "containerUrl": { "type": "string" }, "usage": { "type": "object", "properties": { "ACTOR_COMPUTE_UNITS": { "type": "integer", "example": 0 }, "DATASET_READS": { "type": "integer", "example": 0 }, "DATASET_WRITES": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_READS": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_WRITES": { "type": "integer", "example": 1 }, "KEY_VALUE_STORE_LISTS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_READS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_WRITES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_INTERNAL_GBYTES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_EXTERNAL_GBYTES": { "type": "integer", "example": 0 }, "PROXY_RESIDENTIAL_TRANSFER_GBYTES": { "type": "integer", "example": 0 }, "PROXY_SERPS": { "type": "integer", "example": 0 } } }, "usageTotalUsd": { "type": "number", "example": 0.00005 }, "usageUsd": { "type": "object", "properties": { "ACTOR_COMPUTE_UNITS": { "type": "integer", "example": 0 }, "DATASET_READS": { "type": "integer", "example": 0 }, "DATASET_WRITES": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_READS": { "type": "integer", "example": 0 }, "KEY_VALUE_STORE_WRITES": { "type": "number", "example": 0.00005 }, "KEY_VALUE_STORE_LISTS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_READS": { "type": "integer", "example": 0 }, "REQUEST_QUEUE_WRITES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_INTERNAL_GBYTES": { "type": "integer", "example": 0 }, "DATA_TRANSFER_EXTERNAL_GBYTES": { "type": "integer", "example": 0 }, "PROXY_RESIDENTIAL_TRANSFER_GBYTES": { "type": "integer", "example": 0 }, "PROXY_SERPS": { "type": "integer", "example": 0 } } } } } } } } } } ```