Why we published our showroom calculator to the Shopify App Store

We built the first version of the curtain calculator in 2015 for our own curtain showroom in Lithuania. It was not a product. It was a tool we needed. Every quote was priced by hand out of a supplier catalogue. We were losing evening shoppers because a quote took a day to write.

The calculator we built ran on our own site. A customer picked width, drop, fabric, heading, and lining, and the number came back in seconds. It changed how the shop worked. Two years later we had reached our first million in sales, and by then the fabric vendors calling on us had noticed. They started asking whether we could install it on their other retailers' sites. That was the moment we stopped thinking of it as a tool and started thinking of it as a product.

Why we waited to publish on Shopify

The years between 2017 and 2023 were spent rebuilding the calculator as software rather than a house tool. We had to make it work on any Shopify theme, not just ours. We had to make the pricing tables importable so a retailer could bring in their own pricing without our team touching a spreadsheet. We had to translate the shopper-facing interface into the languages retailers in France, Denmark, and Lithuania actually wanted. And we had to build a way to turn the parent platform into a full retail operation, not just a quoting layer, because that was what the biggest retailers using our early version had told us they needed.

On 27 February 2023 the calculator was published on the Shopify App Store as the Curtain and Blind Calculator. Later that year we rebranded the parent company from Curtains Calculator to InterioApp so the platform side of the business had a name that reflected what it had become.

What we learned

Small retailers do not lose to Amazon on curtains. They lose to whoever answered the quote first. The calculator we built for our own showroom in 2015 was solving the same friction every other retailer sits with; we just met it earlier than most. If a curtain shop can turn a Sunday-night measurement into a paid order by Monday morning, they win. If they have to wait until Tuesday to price it by hand, they do not. That is the whole game, and it is why our own tool became a product.