Can store owners modify the HTML or JavaScript of pages in the checkout flow?

[VaderDidNoWrong]

I provide a shipping forwarding service that enables ecommerce stores who don't support international shipping to target these customers wihtout dealing with the international shipping themselves.

Currently, we have a widget that store owners place on their checkout page to enable customers to sign up for our service during checkout, without leaving the page. This is done through JavaScript, and from my research, it looks like Shopify doesn't allow adding JavaScript to these pages (which makes sense for their use case/business)

An alternative would be to add a link to a page in the checkout flow, which would open a new tab for customers to sign up on.

My two questions are:

1. Can ShopifyPlus stores add JavaScript to a checkout flow page?

2. Can typical (non ShopifyPlus) stores add a link to an external website to a checkout flow page (preferably the shipping address page)?

Thanks!

[Visely-Team · Accepted solution]

The answers would be:

1. absolutely

2. no