Frequently Asked Questions
Everything you need to know about OnChange. If your question is not answered here, reach out to us at contact@onchange.app.
What is OnChange?
OnChange is a website change detection and monitoring platform. It watches web pages and API endpoints on your behalf and alerts you the moment something changes. You can monitor entire pages, specific elements using CSS selectors, or API responses. Notifications are delivered via email, Slack, Discord, or custom webhooks.
How does OnChange detect changes?
OnChange periodically loads your target URL in a real browser environment (or makes an HTTP request for API endpoints), captures the content, and compares it against the previous snapshot. When a difference is detected, it generates a diff showing exactly what changed and sends notifications through your configured channels.
What types of websites can I monitor?
OnChange can monitor any publicly accessible web page, including JavaScript-heavy single-page applications, server-rendered HTML pages, and REST API endpoints. It uses a headless browser for page rendering, so dynamic content generated by JavaScript frameworks (React, Vue, Angular, etc.) is fully supported.
How often can OnChange check for changes?
Check intervals depend on your plan. Free monitors every 30 minutes, Pro every minute, Business every 30 seconds, and Enterprise as often as every 5 seconds. You can also set any custom interval in seconds (minimum 5s, maximum 1 year). Most users find 5-15 minute intervals work well for routine monitoring; flash-sale and time-sensitive use cases are what the sub-minute tiers are for.
What notification channels are supported?
OnChange supports email, Slack (via incoming webhooks), Discord (via webhooks), and custom HTTP webhooks. You can configure multiple notification channels per monitor, and different monitors can use different channels. Webhook payloads include structured data that can be parsed by automation tools like Zapier or Make.
Can I monitor specific parts of a page?
Yes. CSS selector targeting lets you monitor a specific HTML element instead of the whole page. This is the recommended approach for most use cases because it eliminates noise from dynamic content like ads, timestamps, and personalized sections. You can use the visual element picker in the dashboard or manually enter CSS selectors.
Does OnChange support visual (screenshot) comparisons?
Yes. OnChange takes screenshots of monitored pages and provides visual diffs that highlight pixel-level differences. This is particularly useful for detecting layout changes, styling updates, image replacements, and other visual modifications that text-based monitoring might miss.
Can I take a screenshot of a page without setting up a monitor?
Yes. Our free screenshot tool at /tools/screenshot captures any public URL as a PNG in seconds - no sign up required. Pick a viewport (desktop, tablet, mobile), optionally target a specific element by CSS selector, and download the image. If you want to be notified when that page changes in the future, one click turns the URL into a live monitor.
Can I monitor API endpoints?
Yes. OnChange can monitor REST API endpoints and detect changes in JSON response payloads. You can configure custom headers, authentication tokens, HTTP methods, and request bodies. JSON diffs show exactly which fields changed, were added, or were removed. See our API monitoring use case for details.
Is there a free plan?
Yes. The Free plan includes 5 monitors with 30-minute check intervals, email / Slack / Discord / webhook alerts, CSS selector targeting, visual diffs, AI-powered change summaries, WCAG accessibility scans, and full REST API access. It's the same feature set as every paid plan - paid plans just unlock more monitors and faster check frequencies.
How is pricing structured?
Every plan ships with the full feature set. The three things that differ between tiers are (1) how many monitors you can create, (2) how fast checks can run, and (3) audience: Free is for evaluation, Pro for solo developers, Business for growing companies, and Enterprise for mission-critical workloads. There are no hidden fees for alerts, channels, or data storage.
Is my data secure?
All data is transmitted over TLS (HTTPS) and encrypted at rest. Monitored page data is isolated per account and never shared or sold. We're GDPR-ready. Enterprise security reviews, DPAs, and custom data-residency requirements are handled on the Enterprise plan - contact contact@onchange.app.
How long is change history retained?
OnChange retains change history for 90 days on every plan today. Enterprise customers can request longer retention as part of their contract. All change records include timestamps, before/after snapshots, and the full diff data for the duration of the retention window.
Can I access OnChange via an API?
Yes. OnChange provides a full REST API that lets you create, update, delete, and query monitors programmatically. You can also retrieve change history, diff data, and account information via the API. This enables integration with CI/CD pipelines, custom dashboards, and automation workflows.
Can I monitor pages that require login?
For API endpoints, you can configure custom headers with authentication tokens (Bearer tokens, API keys, basic auth). For web pages behind login walls, support depends on the authentication method. Contact us at contact@onchange.app if you need to monitor authenticated web pages.
What happens if a monitored page goes down?
If OnChange cannot load a monitored page (due to a server error, timeout, or network issue), it records the failure and can optionally alert you about the outage. This effectively provides basic uptime monitoring alongside change detection. The monitor continues checking on schedule and resumes normal operation when the page becomes available again.
Can I export my monitoring data?
Yes. You can export change history and monitoring data via the REST API. This allows you to build custom reports, import data into spreadsheets or BI tools, or archive records for compliance purposes. API responses are in standard JSON format for easy integration.
How do I get support?
For general questions, check this FAQ page and our how-to guides. For account-specific issues or feature requests, contact us at contact@onchange.app. We aim to respond to all support requests within one business day.
Explore More
Still Have Questions?
Start monitoring for free or get in touch with our team. We are happy to help.