changed.online is described as a 'free website monitoring service'. After signing up with your email address (and entering a one-time password) you are presented with a dashboard, where you can add pages to track changes on. Features include extracting parts of the web page with CSS and XPATH selectors and simple "line contains" and "line doesn't contain" filters, and notifying about all changes or only added or removed content. Notifications can be delivered by email (optionally signed and/or encrypted), a Slack webhook, or Telegram channel. changed.online alternatives are mainly Website Monitors like VisualPing.io but may also be RSS Readers or Uptime Monitor Services. Filter by these if you want a narrower list of alternatives or looking for a specific functionality of changed.online.