> ## Documentation Index
> Fetch the complete documentation index at: https://docs.natural.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Your party's server-side credential

An API key (`sk_ntl_*`) is your [Party](/guides/concepts/parties)'s server-side credential. A request made with it acts as your party, limited to the scopes the key was created with. Keep it on servers you control, never in a browser or client app.

## Scopes

Every key carries an explicit scope list, so you can create narrow keys for narrow jobs. A call outside the key's scopes is rejected.

## Keys and agents

An API key on its own moves money as a party action. It can attribute a call to an agent, but it remains a party credential; a credential that *is* an agent is an [Agent key](/guides/concepts/agent-keys). See [Authentication](/api-reference/authentication) for the full credential model.

## Secrets

The secret is returned once, on creation, and can never be read again. Revoking a key invalidates it immediately.