XFN is a three-letter abbreviation with multiple meanings. In computing:

In finance:

XHTML Friends Network, a way to add metadata to links suggesting the relationship with that link (friend, co-worker, relative, and so on).

Xinhua Financial Network, the blanket term for the companies and services Xinhua Finance, a financial news company, offers.

X/Open Federated Naming, most commonly implemented as the Federated Naming Service.