# Invoqk API and MCP server

> Validate XRechnung and Peppol e-invoices, convert text to e-invoice XML, and run VAT and late-fee calculators through a REST API or an MCP server. Free API key.

Canonical: https://www.invoqk.com/de/developers

Create a free key in Settings (a verified account is needed). Free accounts get 100 calls a day, Pro gets 5,000. Nothing you send is stored.

## Quickstart

```bash
curl -X POST https://www.invoqk.com/api/v1/einvoice/validate \
  -H "Authorization: Bearer $INVOQK_KEY" \
  -H "Content-Type: application/xml" \
  --data-binary @invoice.xml
```

## Endpoints

- `POST /api/v1/einvoice/validate`: Validate an e-invoice (XRechnung, Peppol BIS, EN 16931 UBL or CII XML, or the XML inside a ZUGFeRD PDF) against the official rules. Returns a verdict, errors, warnings and the parsed invoice. Nothing is stored.
- `POST /api/v1/einvoice/convert`: Turn invoice details into an XRechnung or Peppol BIS e-invoice XML. Plain text is read by rules (any plan). A PDF is read by AI and needs a Pro plan; it uses the same AI quota as the app. The result lists missing fields and validates the XML.
- `POST /api/v1/calc/vat`: Add or remove VAT, or apply reverse charge. Returns net, VAT and gross.
- `POST /api/v1/calc/late-fee`: Late payment fee on an overdue invoice, by a stated monthly percentage or the statutory rule (UK / EU directive).
- `POST /api/v1/calc/hourly`: Invoice total from hours, rate, expenses, discount and tax.
- `POST /api/v1/calc/markup`: Markup and margin from cost and price, or the price from cost and markup percent.
- `POST /api/v1/calc/sales-tax`: Add or remove sales tax at a given rate. Returns net, tax and gross.

The full description is in OpenAPI format: https://www.invoqk.com/openapi.json

## MCP server

The server is remote and uses the same key as a Bearer header.

```bash
claude mcp add --transport http invoqk https://www.invoqk.com/api/mcp \
  --header "Authorization: Bearer $INVOQK_KEY"
```

Tools: `validate_einvoice`, `convert_to_einvoice`, `calculate_vat`, `calculate_late_fee`, `calculate_hourly`, `calculate_markup`, `calculate_sales_tax`.

## Related

- [Invoqk home](https://www.invoqk.com/de)