Why I Built My Own Invoice Automation Tool

Building tools that solve your own problems is underrated. Last year, I was spending roughly 3 hours every month on invoice management—creating PDFs, tracking payments, following up on late invoices. That’s 36 hours a year, or almost a full work week.

So I built something better.

The Problem with Traditional Invoicing

Most invoicing tools are clunky, expensive, or require too much manual intervention. You still have to:

• Create the invoice each time
• Attach it to an email
• Wait for payment
• Follow up manually

My Automation Stack

The solution I built integrates with:

• Stripe for payment processing
• Gmail API for automated follow-ups
• Notion for tracking all invoices

Now, when a client needs an invoice, I run a single command and the entire process happens automatically.

Results After 6 Months

Metric	Before	After
Time per invoice	15 min	30 sec
Late payments	23%	8%
Monthly admin time	3 hours	20 min

The ROI was immediate. I saved 2.5 hours per month, which translates to roughly $1,200 annually in reclaimed time.

The Code

Here’s a simplified version of how the automation works:

async function generateAndSendInvoice(client: Client, amount: number) {
  const invoice = await stripe.invoices.create({
    customer: client.stripeId,
    amount: amount * 100, // cents
  });

  await emailClient.send({
    to: client.email,
    subject: `Invoice #${invoice.number}`,
    attachments: [await generatePDF(invoice)],
  });

  await notion.databases.create({
    parent: INVOICE_DATABASE,
    properties: { /* tracking properties */ }
  });
}

The key insight: automation isn’t about removing humans from the loop entirely. It’s about removing the repetitive, low-value tasks so you can focus on the work that actually matters.

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If you’re interested in a similar setup for your freelance business, reach out. I might open-source a version of this tool soon.