You can preview the extensions by going to the form or portal URL. You can also click Open Extension (portal or shared view) / Share Form (form).
If the Form has no login, click Share Form, then Form for Creating Records to preview creating a new record.
To preview editing a record, click Share Form, then Form for Editing Records. A modal will be displayed. Click Try it out to open a random record or copy and paste the formula, then add it to a new formula field to your table to edit a particular record.
While you're logged in, you can edit your extension while accessing the form or portal. Just click Edit Extension in the bottom left corner. This button is not available on the end user's view.
On the free plan, you're only allowed to preview the extensions yourself. The extension would look and work to your users how it appears to you when you access its URL while logged in.
To visualize the form exactly as your end-users will see it, you can use an incognito/private window or a different browser where you haven't logged in to your miniExtensions account.
Why do I see gears and borders on my fields?
A gear icon appears next to each field on your form. Clicking it provides a shortcut to that field’s settings. These elements are not visible to end users.