# First Request

> Make your first API call to DayZero in under 5 minutes.

- **Category:** Getting Started
- HTML version: https://www.ondayzero.com/docs/guides/first-request
- All guides: https://www.ondayzero.com/docs/guides/index.md
- Endpoint catalog: https://www.ondayzero.com/docs/reference/index.md

---

# Your First Request

Get up and running with the DayZero API in minutes.

## Prerequisites

1. A DayZero account with API access enabled
2. An API token (see [Authentication](/docs/guides/authentication))
3. Your business ID — from the dashboard URL or settings, or from Step 1 below

## Step 1: List Your Businesses

This is the one common endpoint that does **not** need `x-business-id`:

```bash
curl "https://api.ondayzero.com/api/v1/businesses" \
  -H "Authorization: Bearer dz_your_token_here" \
  -H "Accept: application/json"
```

Response (abbreviated — every successful response is wrapped in `{"success": true, "data": …}`):

```json
{
  "success": true,
  "data": {
    "items": [
      {
        "id": "01912345-abcd-7000-8000-000000000001",
        "name": "Acme Corp",
        "default_currency": "USD",
        "accounting_basis": "accrual",
        "created_at": "2026-01-15T10:30:00Z"
      }
    ],
    "next_cursor": null,
    "prev_cursor": null,
    "has_next": false,
    "has_prev": false,
    "limit": null,
    "total": null
  }
}
```

## Step 2: Fetch Transactions

Use the `id` from above as your `x-business-id`:

```bash
curl "https://api.ondayzero.com/api/v1/transactions?limit=5" \
  -H "Authorization: Bearer dz_your_token_here" \
  -H "x-business-id: 01912345-abcd-7000-8000-000000000001" \
  -H "Accept: application/json"
```

The response has the same shape: `data.items` holds the transactions, `data.next_cursor` / `data.has_next` drive paging (see [Pagination](/docs/guides/pagination)).

## Step 3: Create an Invoice

You need a customer first — `GET /api/v1/customers` lists them, `POST /api/v1/customers` creates one. Then:

```bash
curl -X POST "https://api.ondayzero.com/api/v1/invoices" \
  -H "Authorization: Bearer dz_your_token_here" \
  -H "x-business-id: 01912345-abcd-7000-8000-000000000001" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -d '{
    "customer_id": "019ab37c-c057-7000-8000-000000000001",
    "due_date": "2026-11-01",
    "description": "Consulting — October",
    "line_items": [
      {
        "description": "Consulting services",
        "quantity": 1,
        "unit_price": 15000
      }
    ]
  }'
```

A line item with no `variant_id` is a **custom** line: `description` and `unit_price` are required and `quantity` defaults to `1`. To bill a catalog product instead, pass its `variant_id` with a `quantity` (the catalog price is used unless you send `unit_price`).

The response `data` is the created invoice: `id`, `number`, `status` (`draft`), `total`, `balance_due`, the normalised `line_items`, and more.

> **Note:** All amounts are in **cents**. `15000` = $150.00. Never send decimals.

## Step 4: Something went wrong?

Every error is one JSON envelope — `{"error", "message", "code", "request_id"}` — and `422` validation errors add an `errors` map naming the offending fields. See [Error Handling](/docs/guides/error-handling).

## What's Next?

- [Error Handling](/docs/guides/error-handling) — understand API error responses
- [Pagination](/docs/guides/pagination) — navigate large result sets
- [Transactions](/docs/guides/transactions) — work with bank transactions
- [Invoices](/docs/guides/invoices) — finalize, send and record payments
- [Using DayZero from an AI Agent](/docs/guides/ai-agents) — if an agent is making these calls
- [MCP Server](/docs/guides/mcp) — connect AI assistants like Claude and Cursor