# Vultiserver Vultiserver is an infrastructure feature of Vultisig that enables automatic co-signing of transactions within a user's Vault, but only under [pre-defined parameters](/infrastructure/what-is-vultisigner/what-can-be-configured.md) set by the Vault owner. It acts as an automatic co-signer that can also engage when only certain user-defined criteria are met. This functionality allows users to manage a Vultisig "Fast Vault" that inherently functions as a multi-device, multi-factor vault, while providing the user experience of a single-signature wallet when signing transactions.\ This setup is called a 2 of 2 device Fast Vault configuration. Therefore, the Vultiserver feature ensures a smooth "one-device" experience, which (if desired) undergoes automatic security checks on sending that are consistently met once configured. These features can be modified by obtaining the threshold majority of Vault shares and signing a transaction, providing flexibility in maintaining and updating security protocols. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.vultisig.com/infrastructure/what-is-vultisigner.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.