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

# Installation

> Install the Arclasp Python SDK and the framework adapters you need

# Installation

Install the Arclasp-compatible Python package used by Arclasp. Install the core SDK, then add framework-specific extras for whichever orchestration tools you use.

## Requirements

* Python 3.10 or later
* An Arclasp account and API key — sign up at [proofrail.dev](https://proofrail.dev)

## Core SDK

```bash theme={null}
pip install arclasp
```

This installs the framework-agnostic `Chain` context manager, the policy engine, payload sanitization, and the backend HTTP client. Use this directly if you're orchestrating agents yourself.

## Framework adapters

The SDK ships adapters for the most-used agent frameworks. Install only what you need.

<CodeGroup>
  ```bash LangGraph theme={null}
  pip install "arclasp[langgraph]"
  ```

  ```bash LangChain theme={null}
  pip install "arclasp[langchain]"
  ```

  ```bash CrewAI theme={null}
  pip install "arclasp[crewai]"
  ```

  ```bash MCP theme={null}
  pip install "arclasp[mcp]"
  ```

  ```bash All adapters theme={null}
  pip install "arclasp[all]"
  ```
</CodeGroup>

Each extra installs the framework itself if not already present, plus any framework-specific helpers the SDK uses.

<Note>
  **Installing from source instead.** If you're developing against an unreleased SDK change rather than doing normal customer onboarding, install directly from the source checkout: `pip install -e .` from the SDK repo root, or `pip install git+https://github.com/TOAAiV/proofrail` for a specific branch. This is a source-development alternative, not the standard onboarding path.
</Note>

<Note>
  Framework version compatibility is documented per adapter. See [Framework Integration](/frameworks/langgraph) for the pinned ranges. Supported version ranges are pinned in `sdk/pyproject.toml`; install with a compatible framework version in your environment.
</Note>

## Verify your install

```python theme={null}
import arclasp
print(arclasp.__version__)
```

Should print the installed version (e.g., `0.1.0a10`).

## Get your API key

Sign up at [proofrail.dev](https://proofrail.dev). After verifying your email, create an API key from the dashboard. Keys are prefixed with `prail_` and shown once at creation — store yours in a secrets manager or `.env` file.

```bash theme={null}
# .env
ARCLASP_API_KEY=prail_your_key_here
```

## Initialize the SDK

`backend_url` defaults to `http://localhost:8000` for local development. To reach hosted Arclasp, pass it explicitly:

```python theme={null}
import os
import arclasp

arclasp.init(
    api_key=os.environ["ARCLASP_API_KEY"],
    backend_url="https://api.proofrail.dev",
)
```

That's the minimum for hosted use. The SDK has many configuration options for tuning behavior — see [Configuration Reference](/reference/configuration) for the full surface.

## What's next

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Your first governed, approved, and receipted action.
  </Card>

  <Card title="Configuration" icon="gear" href="/reference/configuration">
    Every `init()` parameter, explained.
  </Card>
</CardGroup>