AX2012 Item upload

What is the easiest way to upload item master in AX2012.
I tried excel-addin + CSV upload(for some table)…but this way is not so friendly…
any other easier way is there???

Depends on your definition of “easiest”.

I would advise understanding the tables and then writing development scripts, and as you can tell this is a generic answer, and not the easiers, Excel would be considered the easiest, but then it is the one that takes the longest and is prone to issues.

you can try Rapid Start tool to import your item master.

where can I find this rapid start tool? & how to use it?

Ask you Admin to Register for this service on your partner network a link will be sent , it has module wise template and also parameters setting , you need to download a connector . once all templates are validated and uploaded at one shot these can be imported to AX