Phpseclib

phpseclib is a 3rd-party library which implements SFTP (and SSH2) entirely in native PHP code. It exists in large part because of PHP's native support for SFTP being somewhat undependable and incomplete.

• official site
  • SFTP

Its SFTP class descends from its SSH2 class, so you can use a single SFTP object to handle both (...as I understand it on 2026-07-22; I'm going to be testing that theory soon).