I want to pre populate data from my website into a form

There are 7 data field I wish to populate into a form directly from data on my website.  How can this be done?

You can pre-populate the form fields through the URL parameters. Here's a guide: Prepopulating-Fields-to-Your-JotForm-via-URL-Parameters.

You may also use the Field Prepopulator App in order to pre-register values to some fields. 

Hope that helps. Thank you.

How can I populate a form with data contained on my website that changes for each user. I can make the changing data a form, but it will be submitted by web hook to an API and API will post results on my website.

You can send post data from your form to a custom thank you page using PHP. Please check this guide: Send-POST-Data-From-JotForm-Using-PHP-in-Custom-Thank-You-Page.

We have a guide on how you can set up Webhooks in your form. Here's the guide: How-to-Setup-a-Webhook-with-JotForm.

Please check our API Documentation for more information on you can connect the form to your webpage. Here's the link: http://api.jotform.com/docs/. You can also contact the API team at api@jotform.com.

Let us know if you need further assistance. Thank you.

@Matt

We will resolve your question here https://www.jotform.com/answers/944955

Thanks.

Is it possible to post the external API results on the confirmation/success screen/page that immediately follows form submission? 

Unfortunately, you cannot insert a Javascript code in the default Thank You page. However, you can send POST submission data in the Thank You page. Here's a guide: -How-to-Post-Submission-Data-to-Thank-You-Page.

Hope that helps. Thank you.