Random id values.

[InsipidLake]

{
  "users": [
    {
      "id": 1,
      "name": "John Doe",
      "username": "john.doe",
      "email": "john.doe@example.com",
      "phone": "123-456-7890"
    },
    {
      "id": 2,
      "name": "Jane Doe",
      "username": "jane.doe",
      "email": "jane.doe@example.com",
      "phone": "987-654-3210"
    }
  ]
}

Now if i insert into the API using postman or any other way. The next id comes out randomly "de302" or "7621" or something along those lines.

[textbook]

As oposed to what? That's what's supposed to happen, a random (four character hex) ID gets generated on insertion:

https://github.com/typicode/json-server/blob/e3ce04a04a2777b133a8efa27c59e29121bf24a4/src/service.ts#L108-L110

If you were expecting numerical IDs incrementing from the values you've supplied, that's in the stable v0 but not (currently) the alpha v1:

https://github.com/typicode/json-server/blob/06bdf112aa79ea7a905f927435609ec20a873845/src/server/mixins.js#L50-L51

[typicode]

It's normal behavior. JSON Server v1 expects IDs to be strings, and it returns random ones upon the creation of a new resource.