In one embodiment, a method includes by a host computing server, receiving from a client computing device, a request to upload a multimedia file from the client computing device to a service; by the host computing server, identifying one or more third-party transcoding servers, wherein the transcoding servers are configured to receive and transcode multimedia files from client computing devices and store the transcoded multimedia files; by the host computing server, sending to the client computing device, a reply that comprises addresses of the third-party transcoding servers and job configuration information, wherein the job configuration information specifies one or more upload policies and comprises an access token enabling the client computing device to access the transcoding servers.