How to get notified when a website changes
Published 3 October 2026
You keep going back to the same page to see whether something has changed. A price, a release, a list of openings, a notice. The question is how to make the page tell you instead. The right answer depends on what the site already gives you, so start there before reaching for a tool.
1. Check whether the site has a feed
Many sites publish a feed: a machine-readable list of their newest items. The two common formats are RSS and Atom, both open standards (RSS 2.0, RFC 4287). A feed reader checks the list for you and shows what is new.
If the thing you care about is "a new post appeared", a feed is the cleanest answer, because the site itself is telling you what is new. Nothing has to guess. Its limit is that a feed only covers what the publisher chose to put in it. It will not tell you that a price changed on a product page, or that one line of a policy was edited.
2. Look for the site's own alert
Some sites let you sign up for an email when something happens: "notify me when it's available", "follow this listing", "get updates". When one exists for the exact thing you want, use it. The catch is that these are often limited to accounts, to certain products, or to the events the site decided to support.
3. Watch the page itself
When there is no feed and no alert, the remaining option is a page watcher. A program reads the page on a schedule, remembers what it saw last time, and compares. That is all any of them do. The differences between tools are in how well they cope with the three things that make this harder than it sounds:
- Noise. Pages contain clocks, counters, rotating ads and recommendations. If those count as changes, you get an email every day about nothing.
- Pages you can't see. A page that needs you to sign in can't be read by a program that isn't signed in as you.
- Pages built by scripts. Some pages arrive almost empty and fill themselves in afterwards, so reading the raw page shows nothing.
What it looks like in Osmanth Watch
On 3 October 2026 we pasted https://www.python.org/downloads/ into the box on the home page and typed "tell me when this page changes". This is what the product said back, unedited:
- It read the page straight away and said "We can check this page reliably."
- It understood the request as "Meaningful content change", with the explanation "Alert on meaningful content changes (ignoring timestamps, ads and page chrome)".
- The starting point it recorded was "1180 lines (18,066 characters) of content", taken from the page's main content.
Two details matter here. First, that first reading is only the starting point. It never produces an email, so you are not told about a "change" that is really just the first look. Second, a change to the page is read twice, about ten minutes apart, before we email you. The email goes out only if the second look agrees, so a one-off glitch in loading the page doesn't become an alert.
Then you give an email address and confirm it from the link we send. On the free plan the page is looked at once a day, and you get one email the first time the thing happens, not one every time we look.
What it can't do
A watcher is only as good as what it can read, so here are the limits, in the words the product uses:
- Public pages only. If a page needs someone to sign in, we say so: "This page needs someone to sign in, and we only watch pages that are public."
- Sites that ask not to be visited by programs. Before reading a page we check the site's
robots.txt, the standard way a site says which automated visitors are welcome (RFC 9309). If it asks programs to stay away from that page, we don't read it, and we say so at setup rather than after you have waited a week. - Sites that block automated visits. Some show a check for automated traffic instead of the real page. We tell you we would never see the real content, so you don't start a watch that can never work.
- Between two looks. On the free plan the page is read once a day. Something that appears and disappears in between will be missed.
- When it can't read the page. A watch that can't read the page says "we don't know". It never says "not yet", because those are different answers, and if it has to stop altogether we email you.
Which one to use
If the site has a feed and "a new item" is what you want, use the feed. If the site offers an alert for your exact situation, use that. If neither exists, or you care about a change inside a page, like a price, a policy or a list that is edited rather than added to, watch the page. If you want to narrow a page watch down so it only reacts to the part you care about, monitoring a page without false alarms goes through how. And if what you are really waiting for is stock, getting notified when an item is back in stock covers that case on its own.