Service with test data?

Question

Computer networks

Perhaps a stupid question)
Are there services a la placeholder for various kinds of data?
For example, for training, I want to write an application that will work in real time with different data, where can I get this data from?
As I understand it, you can use the API of some service, for example, the same VK, but it’s interesting that the tools specially sharpened for this business are interesting.

Answer 1

https://jsonplaceholder.typicode.com/