Aquarius provides an API to an off-chain database ("OceanDB") to store and manage metadata about data assets: the assets listed in that marketplace. Every marketplace must run an instance of Aquarius.
An example marketplace front-end for consumers to explore, download, and publish data assets within the Ocean Protocol network. Implemented using [React](https://reactjs.org/) and [🦑 squid-js](https://github.com/oceanprotocol/squid-js).
Client libraries used by applications (such as Pleuston or Jupyter notebooks) to interact with Ocean components, including Keepers, Aquarius nodes, Brizo nodes, etc.
A [Parity Secret Store](https://wiki.parity.io/Secret-Store): software for distributed key pair generation, distributed key storage, and threshold retrieval. It's used to store asset access-control keys.