> ## 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.

# Arcus ERP API

> The complete developer reference for the Arcus ERP public API. Every endpoint tested, built for wholesale distributors.

<img className="block dark:hidden" src="https://mintcdn.com/arcuserp/VQCBFbFEq8yF_wYa/logo/light.png?fit=max&auto=format&n=VQCBFbFEq8yF_wYa&q=85&s=0bc40ae8455c96095ede61b08bd8ee1e" alt="Arcus ERP" height="80" data-path="logo/light.png" />

<img className="hidden dark:block" src="https://mintcdn.com/arcuserp/VQCBFbFEq8yF_wYa/logo/dark.png?fit=max&auto=format&n=VQCBFbFEq8yF_wYa&q=85&s=b541a83f605de090220610d9df8cc610" alt="Arcus ERP" height="80" data-path="logo/dark.png" />

## Welcome

The **Arcus ERP Public API** is a RESTful HTTP API for reading and writing data across every module of the Arcus platform: accounts, orders, products, inventory, fulfillment, purchasing, payments, returns, accounting, and more.

The API is the canonical integration layer for:

* **Data migration** -- import your existing records from a legacy ERP, QuickBooks, or a spreadsheet
* **External integrations** -- connect your warehouse management system, 3PL, or BI tool
* **Automation** -- trigger workflows from external events (Zapier, Make, or bespoke scripts)
* **Custom portals** -- build customer-facing experiences on top of your Arcus data

<CardGroup cols={2}>
  <Card title="Quickstart" icon="bolt" href="/quickstart">
    Send your first request in under 5 minutes.
  </Card>

  <Card title="Authentication" icon="key" href="/authentication">
    Create an API key and understand scopes.
  </Card>

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

  <Card title="SDKs" icon="package" href="/sdks/typescript">
    TypeScript, Python, and Go client libraries.
  </Card>
</CardGroup>

## Design principles

The Arcus API follows the same conventions as Stripe, Plaid, and Shopify. If you have used any of those APIs, you will feel at home immediately.

| Convention            | Description                                                                                                |
| --------------------- | ---------------------------------------------------------------------------------------------------------- |
| **REST**              | Standard HTTP verbs (GET, POST, PATCH, DELETE) on resource paths                                           |
| **JSON**              | Every request and response body is `application/json`                                                      |
| **Bearer auth**       | `Authorization: Bearer <api_key>` on every request                                                         |
| **Entity scoping**    | Entity ID is part of the URL path: `/v1/entities/{entity_id}/{resource}`                                   |
| **Cursor pagination** | `?starting_after=<id>` for all list endpoints (see [Pagination](/concepts/pagination))                     |
| **Expand**            | `?expand[]=customer` to hydrate related resources inline (see [Expand](/concepts/expand))                  |
| **Idempotency**       | `Idempotency-Key: <uuid>` for safe retries on POST/PATCH/DELETE (see [Idempotency](/concepts/idempotency)) |
| **Versioning**        | Date-based `Arcus-Version: YYYY-MM-DD` header (see [Versioning](/concepts/versioning))                     |

## Base URL

All requests go to `https://api.arcuserp.com/v1`. Test mode vs live mode is determined by your API key prefix (`ark_test_*` for sandbox data, `ark_live_*` for production data) -- no separate URL required.

## Need help?

* Browse the [API Reference](/api-reference/introduction) for endpoint-level details
* Read [Concepts](/concepts/idempotency) for deep-dives on pagination, errors, webhooks, and more
* Contact support via the in-app Help button or the [Support](/support) page