The link_url points to the Rutter Link web app, which handles the authentication flow for each Ecommerce platform. Once the merchant completes the Link authentication flow, a CONNECTION_UPDATED event will be fired to your Webhook URL , and you will be able to fetch data for their store through this Connection.
There are a few query parameters that you can specify to a connection URL to customize the authentication experience. Here are some examples:
Loads the authentication flow directly to the Wix-specific step: https://link.rutterapi.com/connection/123?platform=wix
Loads the authentication flow directly to the Wix-specific step and on completion the merchant will be redirected to Google: https://link.rutterapi.com/connection/123?platform=wix&redirect_url=https%3A%2F%2Fwww.google.com
If platform is specified, the Rutter Link flow will start directly at the authentication process for the specified platform, skipping the screen for choosing the platform. See the values in the ENUM column here.
If redirect_url is specified, the merchant will be redirected to the URL specified, and a public_token query parameter for the connection will be added to this url. If the value is https://www.google.com?q=customparameter, the final URL will be https://www.google.com?q=customparameter&public_token=PUBLIC_TOKEN