Hello @clouvi,
Welcome to the Klaviyo Community!
You certainly can manually install the Klaviyo.js on multiple sites. However, keep in mind the main purpose of this would be to collect subscribers from these other sites you own. For example, if you own both an ecommerce site and a blog site. By having the Klaviyo.js installed on both sites, it would allow signup forms to be published even on that blog site that doesn’t have an ecommerce backend.
On the other hand, if you were trying to install the Klaviyo.js on multiple ecommerce sites, I would be weary of this as this could cause potential issues. The most common one being if these alternate sites already have their own Klaviyo account and multiple Klaviyo.js are present. When a site contains multiple Klaviyo.js you’ll often times see issues such as signup forms not appearing, profiles being misappropriately attributed to the different Klaviyo accounts, and the active on-site metrics may not being tracked accurately. For this reason, we suggest having only one set of Klaviyo.js present on any given site and each ecommerce site have their own stand-alone Klaviyo account.
Thankfully, each Klaviyo credential/login supports multi-account access. This means if you need access to different Klaviyo accounts, you can do so from one Klaviyo credential once it has been granted access.
If you haven’t already, I would also suggest taking a look at some other Community posts that touch upon this subject. I’ve included a few below to get you started:
I hope this helps!
David