ChangePreview Autor: NextGen Folks

Review your form changes before you save.

Changed several fields and lost track of what you edited? ChangePreview shows the original value beside your new value, so you can check your work without searching through a long form.

Made for everyday form work
- Entering and checking application details.
- Updating customer records or contact information.
- Editing orders, settings, and administrative forms.
- Testing forms and documenting changes for a support ticket or handover.

Start editing. Open the review when you need it.

On websites you allow in Firefox, ChangePreview starts tracking when the page loads, even with the sidebar closed. Click the toolbar icon or press Alt+Shift+C to review your changes.

With Confirm on save enabled, supported Save or Submit actions also open a confirmation dialog. Choosing “Review in panel” uses the sidebar if it is already open, or opens a separate review window if it is closed.

A clear before-and-after view
- Compare field names, original values, and current values in the Was / Now table.
- Use the numbered button beside a change to find its field on the page.
- Copy a field name or value with its copy button. Text remains selectable.
- Copy or download the comparison as CSV or Markdown.
- Clear detections for the current page to start a fresh comparison.

Optional recovery after a refresh

Turn on Keep after reload to save your changes on this device. After refreshing, review the saved changes and use Reapply my changes on compatible forms. Switching tabs, changing settings, or downloading an export does not itself mean the form needs recovery.

Local processing, no account required

ChangePreview is free, with no subscription, license key, or in-app purchases. It reads form values and page URLs locally to compare edits and match saved changes to the correct page. When Keep after reload is enabled, snapshots stay in Firefox’s local extension storage.

There are no analytics or uploads of form contents to the developer or third parties. You choose when to copy or download an export.

What to know

Forms may contain personal or sensitive information. Password fields and recognized sensitive fields are skipped, but sensitive content in ordinary fields may still be processed locally. Limit site access in Firefox to the websites where you want to use ChangePreview.

Some custom controls, restricted browser pages, closed Shadow DOM, and frames without access are unsupported. Save confirmation and reapplication do not work with every form. Edits made before tracking starts cannot be reconstructed. Review important changes before submitting.

Requires Firefox 140 or later on desktop. Firefox for Android is not supported.

Getting started
1. Install ChangePreview and allow access to the websites where you want to use it.
2. Load or refresh the form page, then make your edits.
3. Open ChangePreview to review your changes before saving.

Built by NextGen Folks
Support: info@nextgenfolks.com
Privacy policy: https://nextgenfolks.com/privacy