Here is a small surprise in Laravel validation. The integer rule passes the string "10" . For a form that is fine, because browsers send everything as text. For a JSON API it is a quiet contract break: your docs say age is an integer, a client sends "age": "10" , and you accept it. Laravel has a one-word fix, integer:strict . I ran both rules against a table of values on Laravel 13.35.0 so you can see exactly what changes, including a few results I did not expect.

The tip in one line

$request -> validate ([ 'age' => [ 'required' , 'integer:strict' ], ]);

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The Laravel documentation describes the strict parameter as considering the field valid only if its type is integer , so strings with integer values are invalid. It also notes that plain integer does not check the PHP variable type, only that the input is accepted by PHP's FILTER_VALIDATE_INT .…