SFTP

SFTP, the SSH File Transfer Protocol, is a network protocol that provides secure file access, transfer, and management over a single, encrypted SSH connection. Despite the similar name it is not FTP-over-SSL; it is a distinct protocol designed by the IETF SECSH working group, and it remains one of the most durable ways two systems move files between each other.

• Runs over SSH - Authentication, integrity, and encryption all ride on an existing SSH channel, so there are no separate data and control ports to secure.
• More than transfer - Beyond upload and download, it supports directory listings, renames, deletes, and resuming interrupted transfers.
• Batch and bulk friendly - It is the default rail for scheduled, high-volume file exchange between enterprises, banks, and partners.
• Ubiquitous tooling - Nearly every operating system, language, and integration platform ships an SFTP client or library.

In the API world SFTP is the workhorse that predates and coexists with REST and Webhooks. A surprising share of the providers I score still expose an SFTP drop-box alongside their web API for bulk data, reconciliation files, and legacy batch integrations. It is not glamorous, but for large, scheduled payloads it is often the most reliable option — and any honest map of an organization’s integration surface has to account for the files quietly moving over SFTP.