Edit: here you can find our research paper describing the protocol more in-depth.
zkCoins is a novel blockchain design with strong privacy and scalability properties. It combines client-side validation with a zero-knowledge proof system. The chain is reduced to a minimum base layer to prevent double spending. Most of the verification complexity is moved off-chain and communicated directly between the individual sender and recipient of a transaction. There are very few global consensus rules, which makes block validation simple. Not even a global UTXO set is required.
In contrast to zk-rollups there is no data availability problem, and no sequencer is required to coordinate a global proof aggregation. The protocol can be implemented as an additional layer contained in Bitcoin's blockchain (similar to RGB[^5] or Taro[^6]) or as a standalone sidechain.
The throughput scales to hundreds of transactions per