noun
A person or entity that sells goods or services. Neutral term used in business and legal contexts.
販売者は商品の品質を保証しなければならない。
The seller must guarantee the quality of the product.
オンラインの販売者から直接購入した。
I bought it directly from an online vendor.
購入者 means 'purchaser' or 'buyer', the opposite party in a transaction.
Compound of 販売 (hanbai, 'selling') + 者 (sha, 'person'). A straightforward Sino-Japanese word.