Why I built KeenInvoice: the invoice mistakes I kept making

I pay people, and companies pay me. That means invoices go both ways, every month, and for years they were a quiet headache. The worst part was always paying others: someone is waiting for their money, the paperwork has to be right, and it is never the most interesting thing on my list that day.

This is the story of how that headache turned into the tool you are reading this on.

The Google Drive years

For a long time my system was a folder in Google Drive. I had a few invoice templates — one per company I bill from, one for the people I pay — and each month I would duplicate last month’s file and edit it.

That was better than starting from a blank page. I did not have to type my address, my bank details or my tax number again. But a template in a document editor only solves the first five minutes. Everything that changes still has to be changed by hand, and that is where it went wrong:

• The invoice number. I duplicated INV-0041 and forgot to make it INV-0042. More than once.
• The date. Last month’s date, sitting there looking perfectly reasonable.
• The amount. I updated the line items and forgot the total, or the other way around. A document editor does not add up.

Most of the time nobody noticed. And that is the problem: a wrong invoice does not fail loudly. Mine came to light months later, when an auditor asked me why two invoices had the same number and why one total did not match the payment. Untangling that took far more time and energy than the invoices ever took to write.

So I built the tool I wanted

I wanted something that keeps the parts that never change and makes it impossible to forget the parts that do. That is KeenInvoice, and I use it myself, every month, for my own companies.

Here is how it answers each of those Google Drive mistakes:

• Numbers count on by themselves. Make a new invoice and it is already INV-0042. With My companies, each business you invoice as keeps its own series, so AR-INV-0007 and INV-0042 never get mixed up.
• Dates are today’s, and due dates follow your terms. Pick Net 30 and the due date is there. No stale dates.
• The arithmetic is done for you. Line totals, discounts, tax per rate, shipping, deposits and the balance due all update as you type, and the PDF is built from the same numbers.
• Templates hold the fixed parts. Save any document as a template, with or without the client and line items, and start the next one in a click. Your logo, signature, bank details and notes come along.
• Many invoices at once, without copy and paste. The bulk invoice generator takes a template and a table where you fill in only what changes — client, items, amounts — or paste straight from a spreadsheet. One click makes them all, numbered in order.
• A record you can check. My documents lists everything you have made, with paid and overdue status, search and a CSV export, so the questions an auditor asks have quick answers.

What is new this week

The latest release adds the features I missed most when billing from more than one business:

• My companies. Save each business you invoice as — its name and address, logo, signature, bank details, currency, tax, colors and number prefix — and switch between them right on the invoice. New documents start as the company you used last, or your default one.
• Signatures. Draw one with your mouse or finger, type it in a handwriting style, upload a scan (the white paper is removed for you), or stamp a Japanese 印鑑 seal. It is kept on your device for next time.
• My templates and the bulk generator, described above.
• 18 color schemes, including two-tone ones, for every design.
• Sharing, with the networks people use where you live, if you want to tell a friend.

Every change is listed in the changelog.

Why your data stays on your device

I deal with my own clients’ names, addresses and amounts, and I did not want them sitting on yet another company’s server. So KeenInvoice keeps everything in your browser: documents, companies, templates, signatures and logos. Nothing you type is uploaded. There is no account to create and no password to forget.

Building it that way meant building a small storage system of its own. Everything saves as you type, and you can come back tomorrow and pick up where you left off. In the same browser, it feels as easy as the paid tools I have used — I would not use it myself otherwise.

The honest trade-off is that your data lives where you made it. To move to another computer, or just to be safe, use Export backup on My documents — it is one small file with everything in it — and Import backup on the other side. The privacy policy explains exactly what is stored and where.

Help me make it better

KeenInvoice is free, and it is built around real invoicing headaches. If something still trips you up, or you have an idea for how a screen should look or work, I would love to hear it. Design ideas are especially welcome — e-mail us at hello@keeninvoice.com.

And if you are still duplicating last month’s invoice in a document editor, try making the next one on the invoice generator instead. It takes about a minute, and the number will be right.