Interactive Form Sandbox
The HTML on the left is interactive, you can change the elements are included and the form to the right will be updated immediately. You can press the blue Submit button on the right to see what data gets sent.
If you already have a trial FormKeep account you can replace
https://formkeep.com/f/exampletoken with your form url from the Setup page and you can see the data get saved and get email notifications as well.