There are existing solutions by Sage certified providers.  If your vendor has to ask, they probably are not authorized.  Check out this solution that has been around for a long time with a proven track record.  

wrightoffice.com/.../

Where is this list of providers who have the ability to link directly with Sage100 Contractor?

Hopefully the Sage City team can answer that for you.  They used to be listed but the entire Sage website changes so often I am unable to locate at this time.  I just tried looking, sorry.

Thank you Char,

Hall Homes I've forwarded this thread and your question onto the Sage 100 Contractor team and have asked them to follow up. Will update you with any news.

Warm Regards, 
Erzsi

Wright Office Solutions can turn an existing Sage PO into an AP invoice from a vendor csv.  I know Eidynamics also does imports.  But we would really love to be able to see all the certified developer solutions right on the Sage website by category!. 

Greetings Hall Homes. I will follow up with you via email.

Cheers,

Kim