Best tool to save data from pre-landing forms

We are looking for ways to save the data filled in by users on a form on pre-landing. The goal is to store the data but also to pass it on as parameters to the affiliate network so the data will be pre-filled on the offer page. I saw a lander where a POST-request is used to store data, wondering if it makes sense to code something like this myself or if there are tools available.

It's very easy to code... since there is a POST requests, you have all the info there, just simply need to store it in the database. The result of the form, will be the final CPA landing with your aff data. It's like HTML/PHP 101.
https://developer.mozilla.org/en-US/docs/Learn/Forms/Sending_and_retrieving_form_data