How I Built a Free Invoice Generator in Python (Replaces Freshbooks $15/mo)

I was paying $15/month for Freshbooks to generate PDF invoices. Then I spent a weekend writing a Python script that does the same thing for free. Here's how it works.

The Problem with SaaS Invoice Tools

SaaS tools like Freshbooks, FreshDesk, and Invoice Ninja are great when you're just starting out. But once you're generating 5-10 invoices a month, you're paying $15-30/month just for PDF generation and email delivery. That's $180-360/year for what is fundamentally a templating + email problem.

The Python Solution

Here's the core invoice generator:

from reportlab.lib.pagesizes import A4
from reportlab.platypus import SimpleDocTemplate, Table, Paragraph
from reportlab.lib.styles import getSampleStyleSheet
from email.mime.multipart import MIMEMultipart
from email.mime.base import MIMEBase
from email import encoders
import smtplib
import os

def generate_invoice(client_name, items, rate=75):
    """Generate a professional PDF invoice and email it."""
    # Create PDF
    filename = f"invoice_{client_name.replace(' ', '_')}_{int(time.time())}.pdf"
    doc = SimpleDocTemplate(filename, pagesize=A4)

    # Build table data
    data = [["Description", "Hours", "Rate", "Amount"]]
    total = 0

    for item in items:
        amount = item["hours"] * rate
        total += amount
        data.append([
            item["description"],
            str(item["hours"]),
            f"${rate}/hr",
            f"${amount:.2f}"
        ])

    data.append(["", "", "TOTAL", f"${total:.2f}"])

    # Create styled table
    table = Table(data)
    story = [table]
    doc.build(story)

    return filename, total

# Usage
invoice_file, total = generate_invoice(
    client_name="Acme Corp",
    items=[
        {"description": "API integration", "hours": 8},
        {"description": "Testing & deployment", "hours": 2}
    ],
    rate=75
)
print(f"Invoice generated: {invoice_file} | Total: ${total}")

Adding Email Delivery

The real magic is sending the invoice automatically:

def send_invoice_email(to_email, invoice_file, client_name, total):
    """Send invoice PDF via email."""
    msg = MIMEMultipart()
    msg['From'] = "[e-mail]"
    msg['To'] = to_email
    msg['Subject'] = f"Invoice - ${total:.2f}"

    # Attach PDF
    with open(invoice_file, 'rb') as f:
        part = MIMEBase('application', 'octet-stream')
        part.set_payload(f.read())
    encoders.encode_base64(part)
    part.add_header('Content-Disposition', f'attachment; filename={invoice_file}')
    msg.attach(part)

    # Send via SMTP
    with smtplib.SMTP_SSL('smtp.gmail.com', 465) as server:
        server.login("[e-mail]", "your_app_password")
        server.send_message(msg)

    print(f"Invoice sent to {client_name} at {to_email}")

The Complete Business Toolkit

This invoice generator is part of a larger Python toolkit I built to replace all my SaaS subscriptions:

• Invoice Generator → replaces Freshbooks ($15/mo → $0)
• Email Campaign Tool → replaces Mailchimp ($20/mo → $0)
• Time Tracker → replaces Toggl ($10/mo → $0)
• Proposal Generator → replaces Proposify ($49/mo → $0)
• Revenue Dashboard → replaces expensive analytics tools

Total annual savings: ~$400/yr

I packaged all 5 scripts into a toolkit: Python Business Automation Toolkit — $9 one-time, includes full source code + documentation.

Why Build It Yourself?

1. No subscription fees — one-time cost
2. Full customization — change templates, add fields, modify logic
3. Data ownership — your invoices stay on your machine
4. No vendor lock-in — migrate or modify anytime

Performance

In 6 months of daily use:

• Generated 80+ invoices (would cost $90 on Freshbooks)
• Saved ~$90 in subscription fees
• Zero downtime (runs locally)
• Full audit trail in local SQLite DB

The 200 lines of Python paid for itself in month 1.

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Want the complete toolkit (all 5 scripts)? Get it here: https://lukassbrad.gumroad.com/l/ugeka — $9 one-time.