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# Invoice Ninja API

> Every Invoice Ninja endpoint on Cotlet: inputs, JSON Schema, cURL, Python and Node.js examples and an example response for each call.

Source: https://cotlet.dev/docs/api/invoice-ninja

Docs sections: [Get started](https://cotlet.dev/docs.md) · [REST API](https://cotlet.dev/docs/api.md) · [MCP](https://cotlet.dev/docs/mcp.md) · [SDKs & CLI](https://cotlet.dev/docs/sdks.md) · [Integrations](https://cotlet.dev/docs/integrations.md)

14 endpoints for Invoice Ninja, each at its own method and path, called with your API key. Open an endpoint for its inputs, examples and response.

- Base URL: `https://cotlet.dev/api/v1/invoice-ninja`
- Connects with: Your own Invoice Ninja account on invoicing.co, with permission to create invoices, quotes, payments and clients
- Integration page: https://cotlet.dev/integrations/invoice-ninja-api-mcp-server

## Read

Return data and change nothing in the account.

| Endpoint | Description |
|---|---|
| [`GET /clients`](https://cotlet.dev/docs/api/invoice-ninja/list_clients.md) | Clients with ID, contact, currency, paid to date and outstanding balance. |
| [`GET /invoices`](https://cotlet.dev/docs/api/invoice-ninja/list_invoices.md) | Invoices with client, status, dates, amount and balance, newest first. |
| [`GET /invoices/{invoice_number}`](https://cotlet.dev/docs/api/invoice-ninja/get_invoice.md) | One invoice with line items, contacts, linked payments and the email history. |
| [`GET /quotes`](https://cotlet.dev/docs/api/invoice-ninja/list_quotes.md) | Quotes with client, status, valid-until date and amount. |
| [`GET /payments`](https://cotlet.dev/docs/api/invoice-ninja/list_payments.md) | Payments with client, date, amount, type, reference and the invoices they were applied to. |
| [`GET /products`](https://cotlet.dev/docs/api/invoice-ninja/list_products.md) | Products from your product library with description and unit price. |

## Write

Change the account. Calls marked Confirm wait for the user to approve them.

| Endpoint | Description |
|---|---|
| [`POST /clients`](https://cotlet.dev/docs/api/invoice-ninja/create_client.md) | Add a client with one contact, optionally with the currency to bill in. |
| [`POST /clients/{client_id}/invoices`](https://cotlet.dev/docs/api/invoice-ninja/create_invoice.md) | Create a draft invoice for a client with line items, dates and notes. |
| [`POST /clients/{client_id}/quotes`](https://cotlet.dev/docs/api/invoice-ninja/create_quote.md) | Create a draft quote for a client with line items and a valid-until date. |
| [`POST /invoices/{invoice_number}`](https://cotlet.dev/docs/api/invoice-ninja/send_invoice.md) (Confirm) | Email an invoice, or a reminder for it, to the contacts that receive it. |
| [`POST /quotes/{quote_number}`](https://cotlet.dev/docs/api/invoice-ninja/send_quote.md) (Confirm) | Email a quote to the contacts that receive it. |
| [`POST /quotes/{quote_number}/to-invoice/convert`](https://cotlet.dev/docs/api/invoice-ninja/convert_quote_to_invoice.md) (Confirm) | Turn an approved quote into an invoice and link the two. |
| [`POST /invoices/{invoice_number}/payments`](https://cotlet.dev/docs/api/invoice-ninja/record_payment.md) (Confirm) | Record money received against an invoice, with date, type and bank reference. |
| [`POST /invoices/{invoice_number}/cancel`](https://cotlet.dev/docs/api/invoice-ninja/cancel_invoice.md) (Confirm) | Cancel a sent invoice: its balance goes to zero and the client balance drops. |

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Cotlet is an independent service. It is not affiliated with, endorsed by or sponsored by any of the products listed on this site. Product names are trademarks of their respective owners.

## For AI agents: sign your user up

Is your user asking you to sign them up for Cotlet? You can do it for them, no account or key needed.

1. Read the fields and their allowed values: GET https://cotlet.dev/api/v1/access-requests
2. Ask the user for each value: email, apps, what you will do with them. If they leave the password to you, generate a strong one and show it to them.
3. Show the user what you will send, then POST it as JSON to https://cotlet.dev/api/v1/access-requests.

One call creates the account and sends the access request; we email the user when access is granted.