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

# Quickstart

> Send your first Arcus API request in under 5 minutes.

## 1. Get an API key

Sign in to [app.arcuserp.com](https://app.arcuserp.com), open **Settings**, then click **Developers**. On the **API Keys** tab, click **Create API key**.

* **Name:** give it a descriptive label (e.g. `My Integration`)
* **Mode:** choose **Test** for sandbox or **Live** for production
* **Scopes:** select at minimum `accounts:read` to follow this guide

You will see the key once. Copy it now.

```bash theme={null}
export ARCUS_API_KEY="ark_test_ent_acme_..."
export ARCUS_ENTITY_ID="your-entity-uuid"
```

<Note>
  API keys are entity-scoped. The entity ID is part of the URL path: `/v1/entities/{entity_id}/{resource}`. Every request is automatically scoped to the entity that issued the key.
</Note>

### Where to find your entity ID

Your entity ID is a UUID that identifies your organization in Arcus. You need it for every API request.

**Easiest way:** Go to **Settings > Developers > API Keys**. The **Quick Reference** panel at the top of the page shows your Entity ID with a copy button right next to it.

<Tip>
  The Quick Reference panel also shows the correct API Base URL for your current mode (Test or Live). Toggle between modes using the Test / Live switcher at the top of the Developers page.
</Tip>

Once you have both values, set them as environment variables:

```bash theme={null}
export ARCUS_API_KEY="ark_test_ent_acme_..."
export ARCUS_ENTITY_ID="xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
```

## 2. Make your first request

List the first five accounts in your entity:

<CodeGroup>
  ```bash cURL theme={null}
  curl https://api.arcuserp.com/v1/entities/$ARCUS_ENTITY_ID/accounts?limit=5 \
    -H "Authorization: Bearer $ARCUS_API_KEY"
  ```

  ```javascript Node theme={null}
  import Arcus from '@arcuserp/sdk-node';

  const arcus = new Arcus({
    apiKey: process.env.ARCUS_API_KEY,
    entityId: process.env.ARCUS_ENTITY_ID,
  });

  const accounts = await arcus.accounts.list({ limit: 5 });
  console.log(accounts.data);
  ```

  ```python Python theme={null}
  from arcuserp import Arcus
  import os

  arcus = Arcus(
      api_key=os.environ['ARCUS_API_KEY'],
      entity_id=os.environ['ARCUS_ENTITY_ID'],
  )

  accounts = arcus.accounts.list(limit=5)
  for a in accounts.data:
      print(a.name)
  ```

  ```go Go theme={null}
  import (
      "context"
      "fmt"
      "os"

      arcus "github.com/arcuserp/sdk-go"
  )

  client := arcus.NewClient(
      os.Getenv("ARCUS_API_KEY"),
      arcus.WithEntityID(os.Getenv("ARCUS_ENTITY_ID")),
  )

  accounts, err := client.Accounts.List(context.Background(), &arcus.AccountListParams{
      Limit: arcus.Int(5),
  })
  if err != nil {
      panic(err)
  }
  for _, a := range accounts.Data {
      fmt.Println(a.Name)
  }
  ```
</CodeGroup>

## 3. Understand the response

Every list endpoint returns the same envelope:

```json theme={null}
{
  "object": "list",
  "data": [
    {
      "id": "acc_01H...",
      "object": "account",
      "name": "Acme Corp",
      "account_type": "business",
      "entity_id": "ent_01H...",
      "created_at": "2024-01-15T10:30:00Z"
    }
  ],
  "has_more": true,
  "url": "/v1/entities/{entity_id}/accounts"
}
```

To get the next page, pass `starting_after` with the last ID in `data`:

```bash theme={null}
curl "https://api.arcuserp.com/v1/entities/$ARCUS_ENTITY_ID/accounts?limit=5&starting_after=acc_01H..." \
  -H "Authorization: Bearer $ARCUS_API_KEY"
```

See [Pagination](/concepts/pagination) for the full cursor contract.

## 4. Create your first order

```bash theme={null}
curl -X POST https://api.arcuserp.com/v1/entities/$ARCUS_ENTITY_ID/orders \
  -H "Authorization: Bearer $ARCUS_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "document_type": "sales_order",
    "account_id": "acc_01H...",
    "line_items": [
      {
        "product_id": "prod_01H...",
        "quantity": 10,
        "unit_price": 25.00
      }
    ]
  }'
```

<Tip>
  Always include an `Idempotency-Key` on POST/PATCH/DELETE requests. If the request fails due to a network error, retrying with the same key returns the original response without creating a duplicate. See [Idempotency](/concepts/idempotency).
</Tip>

## Next steps

<CardGroup cols={2}>
  <Card title="Authentication" icon="key" href="/authentication">
    Entity-scoped keys, scopes, and IP allowlists.
  </Card>

  <Card title="Concepts" icon="book" href="/concepts/idempotency">
    Idempotency, pagination, expand, errors, and more.
  </Card>

  <Card title="API Reference" icon="code" href="/api-reference/introduction">
    Every endpoint documented with try-it-now.
  </Card>

  <Card title="Webhooks" icon="webhook" href="/concepts/webhooks">
    Subscribe to real-time order, payment, and fulfillment events.
  </Card>
</CardGroup>