subcontractor; outsourcing contractor
Refers to an external party to whom work is outsourced; used in business contexts.
We outsourced part of the development to an external contractor.
Careful selection of outsourcing contractors is necessary.
下請け is a more general term for subcontractor, while 外部委託先 specifically emphasizes that the contractor is an external entity to which work is outsourced.
Compound of 外部 (external), 委託 (entrusting/outsourcing), and 先 (destination/party).