PowerShell, 17 bytes
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Slightly unclear on how strict the 'no input' thing is, if it's just no user input or of system input is also disallowed. While my best answer isn't shorter than the other PowerShell answer I think it is novel.

    ps|ConvertTo-Json

Gets running processes (default return is an object) and converts to a json object. Several other two and three letter aliases work.

    gl|ConvertTo-Json
    gci|ConvertTo-Json

You can also take things like inherent type definitions (which are part of the language itself) and pipe them into the conversion function.

    [xml]|ConvertTo-Json
    [int]|ConvertTo-Json