Website Change Monitor: Page & Selector Alerts
Pricing
from $2.00 / 1,000 page checks
Checks web pages or CSS selectors on a schedule and reports each page as changed, unchanged, baseline, selector missing or fetch error, with a line diff. Sends one alert per run to Slack, Discord or a webhook.
One entry per page. Give the full URL. Add a CSS selector to watch only part of the page, for example a price, a table or an article. If the selector stops matching (for example after a redesign), that page is reported as "selector_missing" and the run still finishes. The label is shown in results and alerts.
text: the visible text of the page, or of the elements that match the selector. Markup, scripts and styles are ignored. html: the HTML of the page or of the matched elements, without scripts and styles; use it to catch changed links, images or attributes. selector: the visible text of the matched elements, and every page must have a selector.
Regular expressions for content that should not count as a change. Matching text is removed before the comparison. The defaults remove timestamps, dates, clock times, "5 minutes ago" texts, Unix timestamps, CSRF and nonce tokens, cache-busting query parameters and hashed asset file names. Write /pattern/i to ignore letter case. Remove the date patterns if you want to know when a date on the page changes.
[ "\\b\\d{4}-\\d{2}-\\d{2}[T ]\\d{2}:\\d{2}(?::\\d{2}(?:[.,]\\d+)?)?(?:Z|[+-]\\d{2}:?\\d{2})?\\b", "\\b\\d{4}-\\d{2}-\\d{2}\\b", "\\b\\d{1,2}[/.-]\\d{1,2}[/.-](?:\\d{4}|\\d{2})\\b", "/\\b(?:jan(?:uary)?|feb(?:ruary)?|mar(?:ch)?|apr(?:il)?|may|june?|july?|aug(?:ust)?|sep(?:t(?:ember)?)?|oct(?:ober)?|nov(?:ember)?|dec(?:ember)?)\\.?\\s+\\d{1,2}(?:st|nd|rd|th)?,?\\s+\\d{4}\\b/i", "/\\b\\d{1,2}(?:st|nd|rd|th)?\\s+(?:jan(?:uary)?|feb(?:ruary)?|mar(?:ch)?|apr(?:il)?|may|june?|july?|aug(?:ust)?|sep(?:t(?:ember)?)?|oct(?:ober)?|nov(?:ember)?|dec(?:ember)?)\\.?,?\\s+\\d{4}\\b/i", "/\\b\\d{1,2}:\\d{2}(?::\\d{2})?(?:\\s*[ap]\\.?m\\.?)?/i", "/\\b\\d+\\s+(?:seconds?|secs?|minutes?|mins?|hours?|hrs?|days?|weeks?|months?|years?)\\s+ago\\b/i", "/\\b(?:just now|an? (?:second|minute|hour|day|week|month|year) ago)\\b/i", "\\b1[5-9]\\d{8}(?:\\d{3})?\\b", "/\\b(?:nonce|integrity)=[\"'][^\"']*[\"']/i", "/(?:csrf|xsrf)[\\w-]*[\"']\\s+content=[\"'][^\"']*[\"']/i", "/\\bname=[\"'](?:_token|authenticity_token|csrfmiddlewaretoken|__requestverificationtoken|[\\w-]*(?:csrf|xsrf)[\\w-]*)[\"'][^>]*?\\bvalue=[\"'][^\"']*[\"']/i", "/\\bdata-[\\w-]*(?:csrf|xsrf|nonce|token)[\\w-]*=[\"'][^\"']*[\"']/i", "/[?&](?:v|ver|version|_|t|ts|cb|cache|cachebust|cachebuster|rev|hash|timestamp|nocache)=[^&\"'\\s<>]*/i", "/[.-][0-9a-f]{8,32}(?=\\.(?:js|mjs|css|map|woff2?|ttf|png|jpe?g|gif|svg|webp|ico)\\b)/i"]Report a page as changed only when at least this share of its content changed (0 to 100). With 0, every change is reported. A smaller change is reported as "unchanged" with its percent, and the stored copy is kept, so small changes add up until they pass the threshold.
The most added lines and the most removed lines to include in each result and in the JSON webhook. The total counts are always included.
Also watch a sitemap.xml, a sitemap index, or an RSS or Atom feed, and report URLs added since the last run. Each run adds one result for it: "baseline" on the first run, then "new_urls" with the list of new URLs.
changes: when a page changed, new sitemap URLs appeared, a selector was not found, a page could not be fetched, or the run stopped at its charge limit. always: after every run, with a summary. errors: only when a selector was not found, a page or the sitemap could not be fetched, or the run stopped at its charge limit.
Any URL that accepts a POST request with a JSON body, for example Zapier, Make, n8n or your own server. The body contains the run summary and every result with its diff. Stored encrypted.
A Slack incoming webhook URL (https://hooks.slack.com/services/...). Stored encrypted.
A Discord channel webhook URL (https://discord.com/api/webhooks/...). Stored encrypted.
Name of the stored history. Runs with the same monitor ID compare against each other. If empty, the ID is derived from the page list, so editing the list starts a new history. Set your own ID, for example shop-prices, to keep the history when you add or remove pages. Use different IDs for tasks that must not share history.
Load each page in headless Chrome so that content created by JavaScript is included. Slower, and the default memory goes from 256 MB to 2 GB. Leave it off for normal pages.
How long to wait for each page. A page that takes longer is tried once more and then reported as "fetch_error".