API Reference

Create a document

POST https://slipstack.dev/api/v1/pdf
Authorization: Bearer psk_live_xxx
Content-Type: application/json

{
  "template": "invoice",          // "invoice" | "receipt"
  "options": { "format": "A4" },  // "A4" | "LETTER"
  "data": {
    "from": { "name": "Acme Inc", "address": "1 Market St", "email": "billing@acme.com", "logoUrl": "https://.../logo.png" },
    "to":   { "name": "Globex LLC", "email": "ap@globex.com" },
    "number": "INV-1024",
    "date": "2026-06-09",
    "dueDate": "2026-07-01",
    "currency": "USD",
    "items": [
      { "description": "Consulting", "quantity": 10, "unitPrice": 150 }
    ],
    "taxRate": 8.5,
    "discount": 100,
    "notes": "Thank you for your business.",
    "accentColor": "#1f5be0"
  }
}

Node.js

const res = await fetch("https://slipstack.dev/api/v1/pdf", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.SLIPSTACK_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({ template: "invoice", data: invoice }),
});
const pdf = Buffer.from(await res.arrayBuffer()); // application/pdf

JSON response mode

// Add ?format=base64 or 'Accept: application/json' to get JSON instead of binary:
{
  "pdf_base64": "JVBERi0xLjc...",
  "bytes": 18234,
  "template": "invoice",
  "usage": { "used": 42, "quota": 1000, "plan": "starter" }
}

E-invoices: Factur-X / XRechnung (EN 16931)

POST https://slipstack.dev/api/v1/einvoice         (Pro & Scale plans)
Authorization: Bearer psk_live_xxx
Content-Type: application/json

{
  "options": { "format": "xrechnung-cii" },   // or "facturx-pdf"
  "data": {
    // same shape as /api/v1/pdf, plus:
    "from": { "name": "Acme SARL", "countryCode": "FR",   // required
              "vatId": "FR32123456789" },                  // required if taxRate > 0
    "to":   { "name": "Globex GmbH", "countryCode": "DE" },// required
    "number": "INV-1024", "date": "2026-06-09", "currency": "EUR",
    "items": [ { "description": "Consulting", "quantity": 10, "unitPrice": 150 } ],
    "taxRate": 20,
    "paymentIban": "FR7630006000011234567890189",          // optional
    "paymentReference": "INV-1024",                        // optional
    "buyerReference": "04011000-12345-67"                  // optional (XRechnung BT-10)
  }
}

// "xrechnung-cii"  -> application/xml (EN 16931 CII, XRechnung 3.0 guideline)
// "facturx-pdf"    -> application/pdf with embedded factur-x.xml
//                     (returned format label: "facturx-hybrid (beta)" — the XML
//                     and attachment wiring are spec-correct, but the container
//                     is not certified PDF/A-3)

Parse incoming e-invoices (CII & UBL)

POST https://slipstack.dev/api/v1/einvoice/parse   (any paid plan)
Authorization: Bearer psk_live_xxx
Content-Type: application/xml

<raw CII or UBL e-invoice XML body, max 2 MB>

// Response: normalized JSON
{
  "format": "cii",                        // cii | ubl-invoice | ubl-creditnote
  "profile": "urn:cen.eu:en16931:2017#compliant#...",
  "data": { "from": {...}, "to": {...}, "number": "...", "items": [...] },
  "reported_totals": { "grandTotal": 7339.2, "taxTotal": 1223.2, ... },
  "fields": { "seller_vat_id": "FR32...", "buyer_country": "DE", ... }
}

Errors