This paper presents the tool developed and used during the first year of the European IST project SCALE1 (Internet- Based intelligent tool for Supporting Collaborative Argumentation and Learning). This tool allows argumentative interactions across internet that can be used in pedagogical situations. In adjunction to regular collaborative tools (chat, white board and text editor), a specific collaborative graph editor was designed according to Toulmin's representation of argumentative debate. All the interactions are recorded in structured trace files that can be further studied by the cogniticians and educationalist partners of the project and can be used as examples for teacher training in argumentation. The whole architecture of the system relies on a client-server architecture and uses open Internet protocol technology (XML and Java language). The tool is used via a regular browser, doesn't need any software installation on the client side and has a multi language interface. This modular architecture also enables easy integration of new interactive modules.