changedetection.io

changedetection.io watches web pages for any kind of change and alerts you when it finds one. You give it a URL, set how often to check, and it will email you, send a Slack message, or use any of a dozen other notification methods when the page content differs from the last snapshot. It works for price drops, policy updates, job postings, or anything else you want to track without constant manual refreshing.

The tool stores a visual diff of each change so you can see exactly what was added or removed. It runs as a self-hosted web application using Flask and Playwright for JavaScript-rendered pages, meaning it can handle modern single-page apps and dynamic content. You can deploy it via Docker on any Linux server, or run it directly on Windows or macOS with Python. It integrates with webhooks, Discord, Telegram, Pushover, and many more services. The project uses a simple YAML configuration file and supports proxy settings for privacy.

This is a fully open source project under the Apache 2.0 license, maintained by a single developer (dgtlmoon) with contributions from the community. It is especially popular among sysadmins and devops teams who need to monitor pricing pages, billing dashboards, or documentation for changes. There is no hosted version; you run your own instance, which keeps your data private and gives you full control over check intervals and storage.