MiwoFTP Free. Stellar. 5 Star WordPress.org plugin!! FTP bliss: Nothing to set up. No programs to open/close, start/stop. With this you simply activate the plugin: you can see and access all of the site files, FTP to and from your WordPress website – not a WordPress.com blog.
MiwoFTP is a smart, fast and lightweight file manager plugin. It operates from WordPress back-end so you don’t have to use any FTP program anymore. You can browse folders, create, edit, copy, move, delete, search, upload and download files and much more.
As simple as FTP is, I have had hassles with it. Even when it works, just to do one simple thing sucks when you have to close the browser, open FTP app, login,…etc. Its usefulness surpasses this one function, it is well worth it for FTP alone.
My final word: I have a WP MultiSite, v4.3.1. Activate it per site as needed. I have a huge quantity of active plugins. No conflicts so far.