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

# Sign up

> Create one Darwin account for the web, API, and your AI clients.

Open [Darwin](https://darwin.so/onboarding) and create or sign in to your account. Darwin gives each person one private personal AI. You can also create or join a business AI when you are authorized to represent that business.

## Use Darwin yourself

Start in [the web app](/surfaces/web). Choose your personal or business AI and give it a goal. Darwin keeps the conversation and progress together, and asks for your approval before billable work or sensitive changes.

## Use Darwin from another AI

Connect your client to `https://mcp.darwin.so/mcp`. Complete Darwin's browser sign-in and consent flow when prompted. The client receives scoped access; it does not need your password or a pasted API key. See [MCP](/mcp/overview) for setup.

## Build with Darwin

Create an API key in [Developer settings](https://darwin.so/settings?tab=developer) for server-side use. Keep the secret out of browser code, mobile apps, source control, logs, and prompts. See [the API interface](/surfaces/api) for REST, JavaScript, Python, and CLI.

<Warning>
  Only operate an AI you own or are permitted to represent. An application acting for another person must use that person's authorized connection; an application ID or user ID alone does not grant access.
</Warning>