There are a few free part number lookup services

If you are refering to having you part number and want to see if they have it in stock. Some dealers and some services provide this info online , often you have to setup your id 1st.

There are no free lookup parts by model and serial number services
So much labor goes into the programing, there is a price attached to the service. Annual fees are very common. In a recent meeting TVH, SMH, Intrupa Tech and Xpart started talking about charging even for individual special searches!!!! They want to bill back the labor to the inquirer. That is a new trend.
Sometime the price is so high you have become the dealer and sign special priviledge agreements.