> For the complete documentation index, see [llms.txt](https://docs.vultisig.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.vultisig.com/infrastructure/what-is-vultisigner.md).

# Vultiserver

Vultiserver is the server co-signer for Fast Vaults. One-device signing. Configurable policies are not in the apps yet.

Vultiserver holds one share of a Fast Vault and co-signs with your device. That is a 2-of-2: your device plus the server. You get one-device signing. The complete key is never assembled.

{% hint style="info" %}
Configurable spending limits, address allowlists, and time delays are [not in the apps](/infrastructure/what-is-vultisigner/what-can-be-configured.md). Fast Vault today is password + server auto-cosign after you approve the transaction on your device.
{% endhint %}

See [How a Fast Vault works](/infrastructure/what-is-vultisigner/how-does-vultisigner-work.md) and [Why Vultiserver is safe](/infrastructure/what-is-vultisigner/why-is-it-safe.md).


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