Pmrpc is a HTML5 inter-window cross-domain JSON-RPC based remote procedure call JavaScript library. The library provides a simple API for exposing and calling procedures from windows or iFrames on different domains, without being subject to the same-origin policy. Pmrpc also provides several advanced features: callbacks similar to AJAX calls, ACL-based access control, asynchronous procedure support and fault-tolerance via retries.

The implementation of the library is based on the HTML5 postMessage API, the JSON-RPC protocol and the JSON data format. Pmrpc uses the postMessage API as an underlying communication mechanism and extends it to a RPC model using the JSON-RPC, a transport-independent protocol that uses JSON for formatting messages.

The library is compatible with Firefox 3, Google Chrome, Internet Explorer 8, released under Apache v2.0 license.