Systems and methods provide for efficiently obtaining biometric signatures for electronically signing digital documents. A digital document having a signature field is provided for display on a general computing device. An instruction to obtain a biometric signature from a mobile computing device is received on the general computing device. A remote signing request is sent to a remote server device. The request can include, among other things, an electronic contact address associated with the mobile computing device. Responsive to receiving the request, a Uniform Resource Identifier (URI) is generated, referencing a dynamic application for obtaining the biometric signature on the mobile computing device. The remote server device obtains the biometric signature via the dynamic application or an incoming electronic message from the mobile computing device via the electronic contact address. The biometric signature is communicated to the client device for association with the signature field of the digital document.