NetCommander

This app allows you to manage files on FTP/SFTP servers from the default Files app that you already have on your iPhone and iPad. That includes downloading, uploading, previewing, deleting, and other file management functions.

You can also load your projects from FTP/SFTP and save them there in apps that allow for accessing files. This function includes:
* adding and storing attachments in Mail
* exporting photos from Photos, and Camera
* loading and saving documents in Numbers, Pages, and Keynote
* loading and saving songs in GarageBand
* saving web pages as PDF or Web Archive in Safari
* importing and exporting projects in iMovie
* saving recordings in Voice Memos
* and more!
 
The NetCommander consists of two parts:
* the NetCommander app - allows you to manage FTP/SFTP connections - create, edit, delete and organize them in folders
* the NetCommander File Provider for the operating system - integrates with the operating system of your device - iOS or iPadOS - adding the ability to access FTP/SFTP servers to it

The following file servers are supported:
* SFTP
* FTP
* FTPS - implicit FTP over SSL/TLS
* FTPES - explicit FTP over SSL/TLS

Today, most Linux systems support SFTP or FTPES (also called 'explicit FTPS'). Publicly available file archives that do not need additional security use FTP.

SFTP connections can use a password or key authentication.

If you have multiple mobile devices, your connections will be synchronized between them using iCloud - it may be turned off in the app settings.

More information you can find on the app website.