Abstract: Systems and methods for writing, changing, authenticating and signing web-based documents use an interactive questionnaire methodology and various databases to obtain document content, confirmation of the finality of a proposed document and participant identity verification. Multiple databases may be accessed and/or created to triangulate or otherwise confirm that a purported party to be bound by a legal instrument is the same party adding information to the document and that all parties to be bound by a contract have signed the same final version of the contract. Disclosed embodiments allow participants to change the terms of a proposed agreement that has been signed by others. A modified proposed agreement may be signed by the amending party and then offered to all interested parties.