> ## 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.

# API Reference

> Complete reference for every Arcus ERP API endpoint. Auto-generated from the OpenAPI spec with try-it-now.

## Overview

The Arcus ERP API reference is auto-generated from `arcus-api-v1.yaml`. Every endpoint documented here matches the live API exactly -- there is no drift between the spec and the documentation.

## Try it now

Each endpoint page includes a **Try it now** panel. Enter your API key in the auth panel, fill in the parameters, and click **Send** to fire a real request against your chosen environment.

<Note>
  The try-it-now console fires requests directly from your browser to the Arcus API. Your API key is stored in browser localStorage scoped to `arcuserp.mintlify.app` only and is never sent to Mintlify's servers.
</Note>

## 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.

## Authentication

All endpoints require the `Authorization` header. The entity ID is part of the URL path:

```
Authorization: Bearer <api_key>
URL: /v1/entities/{entity_id}/{resource}
```

See [Authentication](/authentication) for key types, scopes, and security guidance.

## Available resources

| Resource           | Base path                                     | Scopes                                                |
| ------------------ | --------------------------------------------- | ----------------------------------------------------- |
| Accounts           | `/v1/entities/{entity_id}/accounts`           | `accounts:read`, `accounts:write`                     |
| Orders             | `/v1/entities/{entity_id}/orders`             | `orders:read`, `orders:write`                         |
| Products           | `/v1/entities/{entity_id}/products`           | `products:read`, `products:write`                     |
| Inventory          | `/v1/entities/{entity_id}/inventory`          | `inventory:read`, `inventory:write`                   |
| Fulfillment        | `/v1/entities/{entity_id}/fulfillment`        | `fulfillment:read`, `fulfillment:write`               |
| Returns            | `/v1/entities/{entity_id}/returns`            | `returns:read`, `returns:write`                       |
| Purchasing         | `/v1/entities/{entity_id}/purchase-orders`    | `purchasing:read`, `purchasing:write`                 |
| Payments           | `/v1/entities/{entity_id}/payments`           | `payments:read`, `payments:write`                     |
| Accounting         | `/v1/entities/{entity_id}/accounting`         | `accounting:read`, `accounting:write`                 |
| Locations          | `/v1/entities/{entity_id}/locations`          | `locations:read`, `locations:write`                   |
| Payment Terms      | `/v1/entities/{entity_id}/payment-terms`      | `payment_terms:read`, `payment_terms:write`           |
| Units of Measure   | `/v1/entities/{entity_id}/units-of-measure`   | `units_of_measure:read`, `units_of_measure:write`     |
| Sales Channels     | `/v1/entities/{entity_id}/sales-channels`     | `sales_channels:read`, `sales_channels:write`         |
| Pricing Levels     | `/v1/entities/{entity_id}/pricing-levels`     | `pricing_levels:read`, `pricing_levels:write`         |
| Product Categories | `/v1/entities/{entity_id}/product-categories` | `product_categories:read`, `product_categories:write` |
| Tags               | `/v1/entities/{entity_id}/tags`               | `tags:read`, `tags:write`                             |
| Integrations       | `/v1/entities/{entity_id}/integrations`       | `integrations:read`, `integrations:write`             |
| Webhooks           | `/v1/entities/{entity_id}/webhooks`           | `webhooks:read`, `webhooks:write`                     |
| Activity           | `/v1/entities/{entity_id}/activity`           | `activity:read`                                       |
| Migration          | `/v1/entities/{entity_id}/migrations`         | `migrations:read`, `migrations:write`                 |

## Common patterns

Every endpoint follows the same conventions:

* **List endpoints:** `GET /v1/entities/{entity_id}/<resource>` with cursor pagination (`?starting_after=<id>`)
* **Retrieve endpoints:** `GET /v1/entities/{entity_id}/<resource>/:id`
* **Create endpoints:** `POST /v1/entities/{entity_id}/<resource>` with `Idempotency-Key` header
* **Update endpoints:** `PATCH /v1/entities/{entity_id}/<resource>/:id`
* **Delete endpoints:** `DELETE /v1/entities/{entity_id}/<resource>/:id`

See [Pagination](/concepts/pagination), [Idempotency](/concepts/idempotency), and [Errors](/concepts/errors) for the full contract.