HQ9+, 15 bytes

{"Quineland":0}

Outputs itself. I thought an 8-byte answer would be possible, like so:

{":11QQ}

This outputs {":11QQ}{":11QQ}, which is almost valid JSON, but 11QQ is not a valid value.

HQ9+ is not a valid programming language by PPCG standards, so I don't really know if this is valid; please let me know if not.

HQ9+, 15 bytes

{"Quineland":0}

Outputs itself. I thought an 8-byte answer would be possible, like so:

{":11QQ}

This outputs {":11QQ}{":11QQ}, which is almost valid JSON, but 11QQ is not a valid value.

HQ9+ is not a valid programming language by PPCG standards, but the OP has allowed non-programming languages.

HQ9+ is not a valid programming language by PPCG standards, so this doesn't count.

HQ9+, 15 bytes

{"Quineland":0}

Outputs itself. I thought an 8-byte answer would be possible, like so:

{":11QQ}

This outputs {":11QQ}{":11QQ}, which is almost valid JSON, but 11QQ is not a valid value.

HQ9+ is not a valid programming language by PPCG standards, so I don't really know if this is valid; please let me know if not.

HQ9+, 15 bytes

{"Quineland":0}

Outputs itself. I thought an 8-byte answer would be possible, like so:

{":11QQ}

This outputs {":11QQ}{":11QQ}, which is almost valid JSON, but 11QQ is not a valid value.

HQ9+ is not a valid programming language by PPCG standards, so I don't really know if this is valid; please let me know if not.

HQ9+ is not a valid programming language by PPCG standards, so this doesn't count.