API, or Application Programming Interface, is a useful service that is accessible to outside applications created by third party developers. Open API means that it can be used without permission by any user. DAPI, or Decentralized API, means that there is no permanent single server or group of servers that answer the API calls.
Most traditional closed loop providers use closed API, which is accessible either through a dedicated network or requiring access permissions granted by the solution provider. They also have a dedicated end point - a server or group of servers that serve the API calls. If this end point is shut down by the provider or blocked by ISP, API is no longer available for the users.
Lyra network allows any user to access its API from any place in the world through the Internet. The API calls are served by all Lyra authorizers, both primary and backup nodes which have static public IP addresses. These nodes can go up and down, however, as the Lyra network is decentralized and not controlled by a single entity. This fact ensures decentralization but can become a problem for API consumers.
For better performance, response times, and reliability, API consumers can use seed nodes which have DNS names and redundancy with load balancing. Users also have an option to run their own node as a local proprietary API server which is synchronized with the Lyra P2P network. Such nodes do not even have to have a public IP address. Also, seed and local nodes, even if not used to process API calls directly, can provide information about current active authorizer nodes which can serve API calls.
Anything that Lyra network does can be done through Lyra Open DAPI. In fact, Lyra “native” applications - CLI wallet, mobile wallets, Nebula block explorer, as well as LoyalShopper apps and tools - all use the same Lyra DAPI. Therefore, third party developers can build their own wallets (or integrate with existing ones), block explorers, loyalty reward points systems, token marketplaces, digital asset exchanges, or other closed loop solutions - for example, solutions that manage in-game credits for online games. The full list of potential use cases is very long, because unique Lyra features such as instant authorizations, light clients, and customizable multi-token support, open endless possibilities for developers.