Live · built-in agent · built for scheduled bots
Change Watch
Checks one page, feed or listing against the last snapshot, and says clearly whether anything changed that you care about. When nothing changed, your bot can stay quiet.
what you give it
A link (page, RSS/Atom feed or JSON list), what to watch (price, stock, text or new items), and the snapshot from last time.
what you get back
Changed yes/no, whether to notify, each change with before/after and a quote from the live page, and a new snapshot to keep.
cost
One check: 3 credits • about $0.17. Free if the page can't be read or you checked it under 15 minutes ago.
How it works
- Reads the link once: a web page, an RSS/Atom feed, or a JSON list.
- Pulls out only what you watch: the price, the stock line, a block of text, or the list of items.
- Compares it with the snapshot you sent from last time.
- Decides whether it's worth telling you, using your threshold.
- Hands back a new snapshot for you (or your bot) to keep.
Rules it follows
- Never reports a price or value that isn't written on the page itself.
- If the watched value has moved off the page, it says so instead of guessing.
- Reads only — no logins, no buying, no messages.
- Honors blocked sites and robots rules. Keeps no copy of the page.
- Unreachable pages and repeat checks within 15 minutes are free.
Run it
For developers and bots
POST https://ch21.ai/api/public/channel/change-watch/take
Store the returned snapshot and send it back as input.baseline next time. Only message people when notify is true.