API Documentation | Modulus Software

Introduction

The Inventory Manager API is organized around REST principles. Our API accepts JSON-encoded request bodies, returns JSON-encoded responses, and uses standard HTTP response codes, authentication, and verbs.

Base URL

All API requests should be made to:

                    Base URL
                
                    https://api.modulus-software.com/v1

Content Type

All requests must include the following header:

                    Header
                
                    Content-Type: application/json

Authentication

The Inventory Manager API uses API keys to authenticate requests. You can view and manage your API keys in the dashboard under Settings → API Keys.

Keep your API keys secure

Your API keys carry many privileges. Do not share them in publicly accessible areas such as GitHub or client-side code.

Authentication is performed via the Authorization header using Bearer token format:

HTTP Header

Authorization: Bearer your_api_key_here

Example Request

cURL

curl https://api.modulus-software.com/v1/items \
  -H "Authorization: Bearer sk_live_abc123..." \
  -H "Content-Type: application/json"

Rate Limits

To ensure fair usage and maintain API performance, requests are rate limited based on your plan:

Plan	Requests / Minute	Requests / Day
Starter	60	10,000
Professional	300	100,000
Enterprise	1,000	Unlimited

Rate limit information is included in response headers:

                    Response Headers
                
                    X-RateLimit-Limit: 300
X-RateLimit-Remaining: 299
X-RateLimit-Reset: 1640995200

Error Handling

The API uses conventional HTTP response codes to indicate success or failure. Codes in the 2xx range indicate success, 4xx indicate client errors, and 5xx indicate server errors.

200 OK 201 Created 400 Bad Request 401 Unauthorized 403 Forbidden 404 Not Found 429 Rate Limited 500 Server Error

Error Response Format

                    JSON
                

                    {
  "error": {
    "code": "invalid_request",
    "message": "The 'quantity' field must be a positive integer.",
    "field": "quantity"
  }
}
                

List Items

Returns a paginated list of all inventory items for your company.

GET /items

Retrieve all inventory items with optional filtering and pagination.

Query Parameters

Parameter	Type	Description
limit	integer	Number of items to return (default: 50, max: 100)
offset	integer	Number of items to skip for pagination
search	string	Search by name, SKU, or barcode
location	string	Filter by location
low_stock	boolean	Return only items below reorder point

Response

                        JSON Response
                    

                        {
  "data": [
    {
      "id": "item_abc123",
      "name": "Widget Pro X",
      "sku": "WPX-001",
      "quantity": 248,
      "location": "Warehouse A",
      "barcode": "012345678901",
      "reorder_point": 50,
      "created_at": "2025-01-15T10:30:00Z",
      "updated_at": "2025-01-20T14:22:00Z"
    }
  ],
  "pagination": {
    "total": 847,
    "limit": 50,
    "offset": 0,
    "has_more": true
  }
}
                    

Get Item

GET /items/{id}

Retrieve a single inventory item by ID.

Path Parameters

Parameter	Type	Description
idRequired	string	The unique identifier of the item

Create Item

POST /items

Create a new inventory item.

Request Body

Parameter	Type	Description
nameRequired	string	Display name of the item
skuRequired	string	Stock Keeping Unit (must be unique)
quantity	integer	Current quantity in stock (default: 0)
location	string	Storage location
barcode	string	Barcode or QR code value
reorder_point	integer	Quantity threshold for low stock alerts

Example Request

cURL

curl -X POST https://api.modulus-software.com/v1/items \
  -H "Authorization: Bearer sk_live_abc123..." \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Widget Pro X",
    "sku": "WPX-001",
    "quantity": 100,
    "location": "Warehouse A",
    "reorder_point": 25
  }'

Update Item

PUT /items/{id}

Update an existing inventory item. All fields are optional — only provided fields will be updated.

Quantity adjustments

For inventory transactions (receiving stock, adjustments), use the /transactions endpoint instead of directly updating quantity. This ensures proper audit logging.

Delete Item

DELETE /items/{id}

Soft-delete an inventory item. The item will be moved to trash and can be restored within 30 days.

Response

                        JSON Response (204 No Content)
                    
                        // Empty response body on success

List Orders

GET /orders

Retrieve all purchase orders for your company.

Create Order

POST /orders

Create a new purchase order with line items.

Audit Log

GET /audit

Retrieve audit log entries showing all changes to your inventory. Available based on your plan's audit history retention.

Query Parameters

Parameter	Type	Description
action	string	Filter by action type: `create`, `update`, `delete`, `restore`
item_id	string	Filter by specific item
user_id	string	Filter by user who performed action
since	datetime	Return entries after this timestamp (ISO 8601)

Snapshots

GET /snapshots

List all inventory snapshots. Snapshots are point-in-time backups of your entire inventory that can be restored.

Plan limitations

Snapshot creation and restoration frequency depends on your plan. Enterprise plans include daily automatic snapshots.