JSON-RPC (JavaScript Object Notation-Remote Procedure Call) is a JSON-based wire protocol for remote procedure calls (RPC). It is similar to the XML-RPC protocol, defining only a few data types and commands. JSON-RPC allows for notifications (data sent to the server that does not require a response) and for multiple calls to be sent to the server which may be answered asynchronously.

The JSON-RPC protocol is transport-independent and can be carried over many different data transport protocols, including file descriptor I/O, HTTP and TCP. It does not directly provide any support for authentication or authorization.

JSON-RPC works by sending a request to a server implementing this protocol. The client in that case is typically software intending to call a single method of a remote system. Multiple input parameters can be passed to the remote method as an array or object, whereas the method itself can return multiple output data as well. (This depends on the implemented version.)

The receiver of the request must reply with a valid response to all received requests. A response can contain the members mentioned below.

Since there are situations where no response is needed or even desired, notifications were introduced. A notification is similar to a request except for the id, which is not needed because no response will be returned. In this case the id property should be omitted (Version 2.0) or be null (Version 1.0).

In these examples, --> denotes data sent to a service (request), while <-- denotes data coming from a service. Although <-- is often called a response in client–server computing, depending on the JSON-RPC version it does not necessarily imply an answer to a request.