XF 2.2 How build a service to be used for different pages/addons?

[PurplePixel]

Not sure if this is the right space to ask this question, so apologies if it's not.

I am looking for the best way to implement a common function across all pages to be used in my Xenforo.
Reading the documentation, looks like the best way it's to build an add-on, am I right?

I am wondering if exists a way to build a helper?

Thanks

 

[PurplePixel]

Anyone from Xenforo Core Team could provide some suggestions?

Thanks