Generating a clean, professional PDF invoice in code is one of those tasks that looks trivial until you start. You reach for a PDF library, then fight with layout, fonts, multi-currency formatting, VAT/tax math, and right-to-left languages. An hour later you have a brittle template and you still have to maintain it.
This post shows a shortcut: turn one JSON payload into a finished invoice — PDF, JSON totals, or UBL XML — with a single HTTP POST, using the free Invovate API. No PDF library, no template engine.
Try it with zero setup (no API key)
Anonymous calls can compute invoice totals — handy for validating tax/discount math before you render anything:
curl -X POST https://invovate.com/api/generate-invoice \
-H "Content-Type: application/json" \
-d '{
"output": "json",
"from": { "name": "Acme Inc" },
"to": { "name": "Globex LLC" },
"items": [
{ "description": "Consulting", "quantity": 10, "unit_price": 150, "tax_rate": 20 }
]
}'
You get back subtotal, total_tax, and grand_total as JSON. No account needed.
Get a free key (for PDF / UBL / shareable links)
Rendering an actual PDF (or UBL, or a shareable hosted link) needs a free API key:
- Create a free account at invovate.com, verify your email.
- Copy your key from the dashboard — it starts with
inv_. - Pass it as a bearer token:
Authorization: Bearer inv_yourkey.
The free tier is 40 requests/hour, 400/week — plenty to build and run low volume.
Render a PDF (cURL)
curl -X POST https://invovate.com/api/generate-invoice \
-H "Authorization: Bearer inv_YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{
"output": "pdf",
"template": "navy",
"invoice": { "number": "INV-2026-001", "currency": "EUR", "language": "fr" },
"from": { "name": "Acme Inc" },
"to": { "name": "Globex LLC", "address": "1 Rue de Rivoli, Paris" },
"items": [
{ "description": "Consulting", "quantity": 10, "unit_price": 150, "tax_rate": 20 }
]
}' --output invoice.pdf
That's a French-language, EUR, VAT-20% invoice on the navy template — written to invoice.pdf.
Node.js
import { writeFileSync } from "node:fs";
const res = await fetch("https://invovate.com/api/generate-invoice", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.INVOVATE_API_KEY}`,
"Content-Type": "application/json",
},
body: JSON.stringify({
output: "pdf",
invoice: { number: "INV-2026-001", currency: "USD", language: "en" },
from: { name: "Acme Inc" },
to: { name: "Globex LLC" },
items: [{ description: "Website design", quantity: 1, unit_price: 1500, tax_rate: 10 }],
}),
});
writeFileSync("invoice.pdf", Buffer.from(await res.arrayBuffer()));
Prefer a wrapper? There's an SDK: npm i invovate.
Python
import requests
resp = requests.post(
"https://invovate.com/api/generate-invoice",
headers={
"Authorization": f"Bearer {INVOVATE_API_KEY}",
# Set a User-Agent — the CDN in front of the API rejects the default
# python-urllib / bare client UA.
"User-Agent": "my-app/1.0",
},
json={
"output": "pdf",
"invoice": {"number": "INV-2026-001", "currency": "USD"},
"from": {"name": "Acme Inc"},
"to": {"name": "Globex LLC"},
"items": [{"description": "Website design", "quantity": 1, "unit_price": 1500, "tax_rate": 10}],
},
)
open("invoice.pdf", "wb").write(resp.content)
There's a Python SDK too: pip install invovate.
Languages, currencies, and tax
Set invoice.language (11 supported, including ar, ja, hi, ru with proper fonts and RTL) and invoice.currency (20+, with correct symbol/decimal handling). Per-line tax_rate and discount are supported, plus invoice-level global_tax, global_discount, and amount_paid for partial payments. The math comes back identical whether you request json or pdf.
Shareable link + QR code
Add features to get a hosted, shareable invoice URL (and optionally a scan-to-view QR):
{
"output": "json",
"features": { "hosted_link": true, "qr": true },
"invoice": { "currency": "USD" },
"from": { "name": "Acme Inc" },
"to": { "name": "Globex LLC" },
"items": [{ "description": "Retainer", "quantity": 1, "unit_price": 800 }]
}
The response includes a hosted_url you can email to a client — no login on their end.
UBL for e-invoicing
Need a machine-readable invoice? Request "output": "ubl" to get a UBL 2.1 XML document instead of a PDF — useful as a starting point for structured invoice exchange. (Note: Invovate produces the document; it does not submit to national e-invoicing networks.)
For AI agents
If you're building with LLMs, there's an MCP server (npx invovate-mcp) that exposes invoice generation as tools to Claude Desktop, Cursor, and Windsurf — so an assistant can create a real invoice from a natural-language request.
Wrap-up
One POST → a finished invoice. No PDF library to babysit, no template to maintain, and i18n + tax handled for you. The free tier (40 req/hr) is enough to ship a side project or a low-volume integration; paid plans start at $9/mo when you need more.
- API docs: https://invovate.com/api
- Free invoice generator (web): https://invovate.com
- SDKs:
npm i invovate·pip install invovate
Disclosure: I work on Invovate. Feedback welcome — happy to answer API questions in the comments.