An Adapter is software that connects one application to another to exchange data and provide functionality, usually through an API (ApplicationProgrammingInterface) for each application program.

Most modern adapters use Web Services technology ( e.g., XML-RPC? and SOAP?), which is replacing the older CORBA and DCOM protocols for calling remote application services in a Services Oriented Architecture?.

When there is a conversion of the data format, adapters may be called converters.