Python API

Generate invoices and quotes programmatically from Python code.


To start using the gen-invoice Python API, first install the package via pip:

pip3 install gen-invoice

Once the package is installed you will be able to import the API from Python code like so:

import gen_invoice

If you want to generate PDFs then you will also need to install electron-pdf v4.0.6 or newer:

npm install electron-pdf -g

InvoiceGenerator class

Invoice generation functionality is exposed via the InvoiceGenerator class, which provides two public methods. These methods are documented below.

generate() Method

Generates an invoice/quote with the specified options.


  • outfile: (string) the path to the output HTML file.
  • number: (string) the invoice number.
  • items: (list) the list of line items.
  • payee: (dictionary) the payee details.
  • payer: (dictionary) the payer details.
  • template: (string) the Jinja template HTML.
  • stylesheet: (string) the stylesheet CSS.
  • tax: (float) the tax (GST, VAT, etc.) to apply to the total of all line items. Defaults to 0.0.
  • is_international: (boolean) specifies whether the invoice/quote is for an international recipient. Defaults to False.
  • is_quote: (boolean) specifies whether we are generating a quote rather than an invoice. Defaults to False.
  • expiry: (string) if we are generating a quote, specifies the expiry date of the quote. Defaults to None.
  • purchase_order: (string) if we are generating an invoice, specifies the purchase order number that the invoice relates to. Defaults to None.
  • context_overrides: (dictionary) custom overrides to apply to our context data prior to passing it to the Jinja template. Defaults to None.


  • (dictionary) the context data that was passed to the Jinja template.


  • May throw system-generated errors in the event of file permission issues or receiving malformed line item data. May also throw Jinja-generated errors in the event of receiving malformed template HTML.

render() Method

Renders an invoice/quote HTML file to a PDF using electron-pdf.


  • html: (string) the path to the input HTML file.
  • pdf: (string) the path to the output PDF file.


  • (boolean) True if the PDF was rendered successfully, or False if electron-pdf v4.0.6 or newer could not be found.


  • RuntimeError if the PDF could not be rendered successfully, or CalledProcessError if the electron-pdf subprocess returned a non-zero exit code. May also throw other system-generated errors in the event of file permission issues.

Usage example

Example code for using these methods is shown below:

#!/usr/bin/env python3
from gen_invoice import InvoiceGenerator, Utility

# Our output file paths
OUTFILE_HTML = "/path/to/output.html"
OUTFILE_PDF = "/path/to/output.pdf"

# Load our template and stylesheet data from file
template = Utility.read_file("template.html")
stylesheet = Utility.read_file("stylesheet.css")

# Generate our invoice
generator = InvoiceGenerator()
  # Our output HTML file
  outfile = OUTFILE_HTML,
  # Our invoice number
  number = "INV001",
  # Our line items
  items = [
      "Section": "Materials",
      "Item": "Widget A",
      "Quantity": "20",
      "Units": "pcs",
      "Price": "12.99"
  # Our payee details
  payee = {
    "name": "XYZ Widget Company",
    "identifier": "123456789",
    "email": "",
    "address": [
      "1 Widget Road",
      "WID 9999"
    "bank": {
      "holder": "XYZ Widget Company",
      "bank": "Acme Banking Co",
      "code": "123-456",
      "account": "192837465"
  # Our payer details
  payer = {
    "name": "XYZ Widget Company",
    "address": [
      "1 Widget Road",
      "WID 9999"
    "due": "Within 30 days of receipt"
  # Our template and stylesheet
  template = template,
  stylesheet = stylesheet,
  # No tax
  tax = 0.0,
  # Generate a domestic invoice rather than an international one
  is_international = False,
  # Generate an invoice rather than a quote
  is_quote = False

# Render the invoice HTML to a PDF file using electron-pdf
generator.render(OUTFILE_HTML, OUTFILE_PDF)