Can you raffle your personal items online in California?

No, you cannot raffle your personal items either online or offline in California, unless you are a bona fidecharitable (or, in some cases, other nonprofit) organization. It is prohibited by anti-gambling provisions in the California constitution.

In order to conduct a raffle, at least 90% of the proceeds must go to "charitable or beneficial purposes in California". Making money for yourself, while it does benefit you, is not considered a "beneficial purpose".