Is it possible to create an Authorize.net payment form with user defined amount?

Hi My client wants to use authorize.net and have clients stay on his site, if use an iframe embed is this how it will work. If he wants his page to look secure then he can just buy an SSL certificate. Also I remember the paypal forms had an option to make a User-filled Price field, this is for invoices, so amount is always different, so user needs to input a unique amount for the sale and also need fields for name, email and address and then email customer an invoice, is all this possible?

Hello,

Yes, you can use the iFrame embed method and embed your form in the secure website so your submissions and data is secure.

If you are referring to custom amount field where your clients can input the price manually, that is possible with both PayPal and Authorize.net. 

Basic contact fields you can simply create by using the form builder:

If you need any further assistance or had something else in mind, please let us know.

Thank you!