From quote builder to quote & invoice builder — what I added and why
A few weeks ago I launched a standalone Quote Builder on Gumroad. No signups, no subscriptions, just a single HTML file that runs in your browser.
The feedback I kept seeing: "great, but what about invoices?"
So I built it in. One tool, two modes. You build your quote, hit "Convert to Invoice", and all your data carries over automatically. The reference number switches from QT- to INV-, the due date updates, and a payment details block appears on the document.
I also added:
- PAID stamp with custom date
- Separate auto-incrementing counters for quotes and invoices
- Payment details field (IBAN, bank, PayPal)
- "Amount Due" instead of "Total" on invoices
It's still a single HTML file. No account, no cloud, no subscription. $19 one-time.
Launching on Product Hunt this Tuesday (June 30) if anyone wants to support: https://dewinterronald.gumroad.com/l/quote-invoice-builder
Happy to answer questions about the build.
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I like that you didn't treat "can you add invoices?" as a feature request. It was really users telling you where they expected the workflow to end. A quote and an invoice aren't separate jobs in their mind—they're two steps in the same one. Expanding the product around that workflow feels much stronger than simply expanding the feature list.