Update: this is probably no longer needed, i found service which does this. see the footer of this post.

Hello, it would be good to have simple service where member can register and add some urls and when there is an change on the page (script periodically download that page and compare with latest version), an email is sent to the member.

- member set maximum frequency to send email, or send daily, weekly, monthly digest
- in email which is sent on page change is listed part of updated content, there is limit in characters to put into email so email is not too big.
- an email contains link to the monitored page, but it links to our website where is an iframe to the monitored page - on the top can be an advertisement banner and in bottom part monitored page + link to delete/modiffy this page monitoring.

- sites with size above 5mb wont be monitored.
- the small changes like number change do not trigger alert email (example: date on the webpage change, so it dont send false positive)
- member can select exact regex which will be watched. If this regex changes or appears, alert is sent
- one IP can add up to 20 monitored pages / 24 hours or warning is shown: Too many pages added.

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Here are the services for websites change monitoring:
https://internetlifeforum.com/internet/792-how-monitor-some-website-changes-tool/
http://downloadsquad.switched.com/2010/02/08/10-free-ways-to-keep-track-of-changes-to-any-website-without-rss/