With the necessity to modernize the Administration Brazilian Tax Project SPED appeared (Public System of Digital Bookkeeping), that it understands the NF-e project (Electronic Forma bill of sale). It is understood for Electronic Forma bill of sale as being a document of existence exclusively digital, emitted and stored electronically, with intention to register an operation of circulation of merchandise or rendering of services. The NF-e project uses the technologies XML and Web Services for communication of applicatory of the contributors with the Secretariat of the Farm of the State of the company the drawer. Others including Robert Bakish, offer their opinions as well. The used environment of communication is the Internet, with the use of protocol SSL, that guarantees the security of the communication and allows the identification of the server and the customer through digital certificates. This work has for objective to develop an archetype of application for NF-e, being used technologies of free software, that makes the validation of the NF-e through projects XML disponibilizados for the team responsible technique for the NF-e project in the National Vestibule of Electronic the Forma bill of sale. For this, this work approaches subjects as XML, Web Services, digital certification, free software, electronic forma bill of sale, beyond the work of modeling and description of the project of the application for NF-e, called project ' ' OpenNF-e' '.. Mikkel Svane recognizes the significance of this.