How trust-worthy are the Spinner smart contracts?
At beta stage, not so much. Users are advised to only make small deposits that they can afford to lose. Bugs or unforeseen issues are highly unlikely but still possible.
Before official launch, everything will be open source and made ready for security audits. You will also be able to check what was deployed matches what the source code compiles to.
Lastly Spinner smart contracts will either be immutable or controlled by the Spinner DAO, a decentralized governance entirely run by Spinner users.
Are Spinner transactions 100% private and anonymous?
First of all, privacy and anonymity are not equal concepts. Privacy means keeping what you know (or do) private but not necessarily hiding your identity, while anonymity means disassociate your true identity from what you do, which may very well be public.
Spinner sort of does both. Only the owner of private notes knows the balance and transactions they conducted on the Spinner ledger, which implies privacy. While public withdrawals or deposits are visible, no one can draw the dots between them, which is a form of anonymity.
What is the difference between Spinner and Zcash?
Zcash was a pioneer in applying zk-SNARK to blockchains, and has popularized private transaction concepts like shielding/unshielding which are now well understood. But Zcash (or Monero) is a layer-1 blockchain with its own consensus protocol, PoW mining, etc. which are more of an infrastructure concern. Besides, they lack smart contract abilities and can only support their own native tokens.
Spinner on the other hand is an application built on top of a blockchain. It specifically wants to take advantage of IC's web-serving canisters, infinite scalability, and most importantly, the upcoming threshold ECDSA feature that will put an end to the hot mess created by cross-chain bridges.
What is the difference between Spinner and Tornado Cash?
Spinner's design was influenced by Tornado Cash. However, Spinner was built from ground up as a native application on the Internet Computer, leveraging cutting edge technologies such as orthogonal persistence and web-serving smart contracts, as well as its reverse gas model. We hope to bring better user experiences and versatile utilities reaching beyond a single chain.
The most crucial difference, however, is that Tornado Cash has to deploy separate smart contracts on each chain it supports, while Spinner smart contracts are all part of one integral application running on IC supporting tokens on other chains. Expect more privacy and interoperability between chains and tokens!