Cyberduck - A libre FTP, SFTP, WebDAV, S3, Backblaze B2, Azure & OpenStack Swift browser.
CompleteFTP by EnterpriseDT - CompleteFTP is a secure FTPS and SFTP server for Windows.
ProjectSend - ProjectSend is a self-hosted application that lets users upload files and assign them to specific clients.
SolarWinds Serv-U - SolarWinds Serv-U is a web-based, secure file transfer solution.
Filestack - Simple file uploader and robust APIs for uploading, transforming, and delivering any file into your app. Filestack is a collection of tools and powerful APIs that make it simple to upload, transform, and deliver content.
Progress WS_FTP - Progress WS_FTP is a robust FTP server solution that enables you to keep an eye on transfer details and security, accelerate file transfers, and protect your data with advanced settings and controls.