This free online tool allows to generate JSON dataset. You can generate multiple JSON files exported to a zip archive. No limits. No registration.
CSV Explorer - Explore Spreadsheets with Millions of Rows
Mockaroo - A realistic data generator to test your app
Modern CSV - A CSV editor/viewer
JSON Generator - Create mock and sample JSON using a powerful template syntax
Doypp - The Easiest Way to Build Content-Based Mobile Apps
Sbored. - Discover things to do in your free time