Create Invoice Ninja invoices from a billing list

1. Open Invoices and create a new invoice, then pick the client. The client drives the currency, tax rules, language, payment terms and email templates.
2. Add one line per item with Product, Description, Unit Cost and Quantity. Quantity takes up to six decimals, so 12.5 hours works.
3. Set the Invoice Date and the Due Date, then save. The invoice stays a draft: the client cannot see it and the client balance does not change.
4. Choose More Actions > Email Invoice to send it to the contacts checked to receive it. Contacts with Add to Invoices enabled on the client are pre-selected.
5. Repeat for every client on the list. Invoice Ninja bills the same lines every cycle with a Recurring Invoice, but nothing fills in hours that change each month.

Here is the billing list: client, hours and rate. Create one draft invoice per client in Invoice Ninja, show me the totals, and send them after I say OK. Stop on any client name that matches nothing or two clients.

1. 01

   Match every name to a client

   Your agent looks each name up with list_clients. A name that matches no client or two clients stops the run for that line and is reported, so no duplicate client is created and no invoice goes to the wrong one.

2. 02

   Take prices from the right place

   When a line names a product, list_products supplies its description and price, as the invoice form does. The rate in your list wins over the product price, and the agent says which one it used.

3. 03

   Create the drafts

   create_invoice builds one draft per client with the invoice date and a due date from your terms, and returns the invoice number. Drafts reach nobody, so this step needs no OK.

4. 04

   Check every total

   The agent adds up quantity times unit cost per line and compares the sum to the amount Invoice Ninja returned and to the total on your list. Any difference is shown before anything is sent.

5. 05

   Send after your OK

   send_invoice emails each invoice and moves it from Draft to Sent, which raises the client balance and starts the reminder schedule. Each send waits for your OK by default.

Billing list: 5 clients
Created 4 drafts, total 4,635.00 USD, none sent yet:
- INV-0043 Northwind Studio, 1,050.00 (10 h design sprint at 90.00, hosting setup 150.00)
- INV-0044 Brightwave Ltd, 1,700.00 (20 h at 85.00)
- INV-0045 Kestrel Labs, 1,125.00 (12.5 h at 90.00)
- INV-0046 Orchard & Finch, 760.00 (8 h at 95.00)
Needs you: "Fenwick" matches Fenwick Ltd and Fenwick Group

curl -X POST https://cotlet.dev/api/v1/invoice-ninja/clients/Wp3xq8Rnd5/invoices \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"items":[{"product":"Design sprint","description":"Design sprint, 10 hours","unit_cost":90,"quantity":10},{"product":"Hosting setup","description":"Hosting setup","unit_cost":150,"quantity":1}],"invoice_date":"2026-10-14","due_date":"2026-11-13"}'

{
  "invoice_number": "INV-0043",
  "client": "Northwind Studio",
  "status": "draft",
  "invoice_date": "2026-10-14",
  "due_date": "2026-11-13",
  "currency": "USD",
  "items": [
    {
      "product": "Design sprint",
      "description": "Design sprint, 10 hours",
      "unit_cost": 90,
      "quantity": 10,
      "line_total": 900
    },
    {
      "product": "Hosting setup",
      "description": "Hosting setup",
      "unit_cost": 150,
      "quantity": 1,
      "line_total": 150
    }
  ],
  "amount": 1050,
  "balance": 1050
}

MCP: add https://cotlet.dev/mcp/v1 with the same key; the call is invoice_ninja_write → create_invoice. Example data.

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