Mockaroo - A realistic data generator to test your app
Thunkable - Powerful but easy to use, drag-and-drop mobile app builder.
JSON Generator - Create mock and sample JSON using a powerful template syntax
MIT App Inventor - App Inventor is a cloud-based tool, which means you can create apps for phones or tablets right in your web browser.
Softbuilder SB Data Generator - SB Data Generator is a simple and powerful tool to generate and populate selected tables or entire databases with realistic test data.
Bubble.io - Building tech is slow and expensive. Bubble is the most powerful no-code platform for creating digital products.