Free Invoice API — Generate Invoices via URL

How It Works

ZapInvoice's URL-based API lets you generate invoices by constructing a simple URL. No authentication, no rate limits, no API key. The invoice renders instantly in the browser and can be downloaded as PDF.

Base URL

https://zapinvoice.web.app/i?{parameters}

Parameters

Parameter	Description	Example
`from`	Your business name / sender	`from=Acme%20LLC`
`to`	Client / recipient name	`to=Client%20Corp`
`item1`	Line item: Description\|Qty\|Rate	`item1=Design\|5\|100`
`item2...N`	Additional line items (up to 20)	`item2=Dev\|10\|150`
`tax`	Tax rate as percentage	`tax=8.5`
`currency`	Currency code (USD, EUR, GBP, JPY, CAD, AUD, INR, BRL)	`currency=EUR`
`due`	Due date	`due=2026-04-01`
`notes`	Additional notes on invoice	`notes=Net%2030`
`number`	Invoice number	`number=INV-001`

Examples

Simple Invoice

      
      https://zapinvoice.web.app/i?from=John%20Doe&to=Acme%20Corp&item1=Consulting|10|150&currency=USD
    

Multi-Item Invoice with Tax

      
      https://zapinvoice.web.app/i?from=Design%20Studio&to=Tech%20Inc
&item1=Logo%20Design|1|500
&item2=Brand%20Guide|1|300
&item3=Social%20Assets|5|100
&tax=10
&currency=USD
&number=INV-2026-042
    

JavaScript / Node.js

      
      // Generate an invoice URL programmatically
const params = new URLSearchParams({
  from: 'Your Company',
  to: 'Client Name',
  item1: 'Web Development|10|150',
  item2: 'Hosting Setup|1|200',
  tax: '8',
  currency: 'USD',
  number: 'INV-001'
});

const invoiceUrl = `https://zapinvoice.web.app/i?${params}`;
// Send this URL to your client — they can view + download the PDF
    

Python

from urllib.parse import urlencode

params = {
    "from": "Your Company",
    "to": "Client Name",
    "item1": "Consulting|20|200",
    "tax": "10",
    "currency": "USD",
}

url = f"https://zapinvoice.web.app/i?{urlencode(params)}"
# Share this URL — recipient sees a professional invoice

cURL / Automation

# Open invoice in default browser
open "https://zapinvoice.web.app/i?from=Freelancer&to=Client&item1=Work|1|500"

# Or use in a Zapier/Make webhook to auto-generate invoices

Use Cases

🔧 SaaS Platforms

Add invoice generation to your freelancer marketplace, CRM, or project management tool.

🤖 Automation

Generate invoices from Zapier, Make, n8n, or any workflow tool using URL webhooks.

📧 Email Invoicing

Include invoice links in automated emails. Clients click to view and download.

💬 Chat & Messaging

Send invoice links via WhatsApp, Slack, Telegram, or any messaging platform.

📱 Mobile Apps

Open the URL in a WebView for instant invoice generation in your mobile app.

📊 Spreadsheets

Use HYPERLINK() in Google Sheets to generate invoices from your billing data.

Embed Widget

Want to add invoice generation directly to your website? Use our free embeddable widget. Get the embed code →

FAQ

Is it really free?

Yes, completely free. No API key, no rate limits, no signup required. Generated invoices include a small "Powered by ZapInvoice" footer.

Is there a rate limit?

No hard rate limit. The API runs on Firebase global CDN, so it's fast worldwide. For high volume use, contact us for a dedicated setup.

Can I remove the ZapInvoice branding?

The Pro plan ($7/month) removes branding and adds custom logo support. Learn more →

Do you store any data?

No. Invoices are generated entirely in the browser. We don't store, log, or transmit your invoice data. Everything stays on the recipient's device.