The first party Crockford implementation? Not free software. The specification diagrams or text on json.org? Similarly non free. The JSON format itself? Argua

The first party Crockford implementation? Not free software. The specification diagrams or text on json.org? Similarly non free. The JSON format itself? Arguably not copyrightable. Maybe patentable, had Crockford tried 20 years ago, but that's more an argument for the lunacy of many software patents. If you're concerned about the implications of the JSON license on JSON implementations, wait until you hear about the ISO8601 spec's license