Flatfile - The new standard for data import
CarrierWave - Solution for file uploads for Rails, Sinatra and other Ruby web frameworks.
Backand - Backand is a backend-as-a-service for AngularJS that provides out-of-the-box social login, push notifications, Ionic integration and more.
Uppy - The next open source file uploader for web browsers
csvbox - Spreadsheet importer for your web app, SaaS or API
tus.io - File Uploads