An API integration makes two programs pass data to each other by themselves, so nobody copies an order, an address or an invoice from one screen into another.
We build custom API integrations for small businesses whose tools come without a ready-made connector, or whose connector stops one step before the part that eats the day. The order desk of our own parts business is the example on this page: eight connections, one screen for the people packing.
Grouped by the kind of system on the other side. Each one is in production for our own businesses or for a client.
Invent fetches eBay orders by itself. When a listing says “lot of 6”, it works out how many units that is and pairs the order with the box that holds them, and the tracking number goes back to eBay on its own.
The Kakapo Press shop keeps its books in step with AbeBooks. It always sends the complete record, because a partial update there wipes the fields it leaves out, and it withdraws a book from the marketplace only after confirming the sale on that book’s own listing page.
A Hungarian shipping broker gave us the European carriers in one connection. For the main FedEx lanes we added a direct one a few weeks later, because that route allows electronic customs papers and courier pickups.
Book before half past twelve and FedEx collects the same day; later bookings move to the next working day, skipping weekends and Hungarian public holidays, the moving Easter ones included.
Invoices go out through számlázz.hu with the VAT treatment worked out per buyer: Hungarian VAT at home, reverse charge for EU businesses with a valid VAT number, zero-rated export outside the EU. A VAT number typed into a checkout note is checked against the EU register first.
The bookshop’s invoices use the EU margin scheme for second-hand books. One button issues the invoice once, and it refuses any order marked as a test.
Kakapo’s checkout hands the buyer to a hosted card page. A signed message from the payment provider marks the order paid exactly once, and if that message goes missing, a scheduled job asks the provider and recovers the order.
On the Iron Rainbow marketplace every payment is shared between the coating shop, Iron Rainbow, a marketing budget and any partner who handled the job. The rules live in one place with tests that check the amounts.
The bookshop sends Google Merchant Center a feed of every book with a photograph, shipping cost per country included. Advertising tags load only after the visitor agrees.
Iron Rainbow’s content engine publishes to seven platforms, with tracked short links that show which post sent people to the site, and brings new comments back in.
In the CRM we built for Iron Rainbow, replies to outreach emails come back in on their own, and anyone who answers STOP is never written to again. When a shop fills in the website form, it is matched to the shop already on file and the team chat gets an alert.
Calls on the business line are transcribed on our own servers, and the onboarding answers go straight into the shop’s profile.
Shops, marketplaces, carriers and invoicing services we have connected for our own businesses and for clients.
Most of the work goes into the cases where something goes wrong: a missing field, a message that never arrives, a key that expires.
If two popular apps need one simple step between them, a few dozen times a month, Zapier or Make will do it for a monthly fee and no build. We would tell you that on the call.
A custom integration pays when the step needs your own rules, when the service is missing from the connector’s list, or when a double send costs money. When each one fits
Code written for your business that connects two or more systems through their APIs and applies your own rules on the way: which carrier, which VAT line, which box. A ready-made connector moves the data; a custom integration also makes the decisions your staff make today.
It depends on the other side. Our order desk was connected to eBay and booked its first live label through the shipping broker in May 2026, and the direct FedEx connection followed a few weeks later. Our fixed eBay listing package goes live in 2 to 3 weeks.
We price it on a call, per milestone, once we have read the other side’s documentation. Most integrations are part of a bigger build; see what custom software costs. For eBay sellers there are fixed packages on the services page.
Care covers it: services change their rules and we change the integration. Right now the bookshop is waiting for a new access key from AbeBooks; Kakapo holds every change in its queue until it arrives, and the shop’s own two-hourly check keeps it in step meanwhile.
Yes. We connect Shopify, WordPress and WooCommerce shops, eBay, Etsy and Jófogás, QuickBooks, Stripe, PayPal, Revolut Business and Wise, UPS, USPS, FedEx, DHL and TNT, the main Hungarian carriers and the Hungarian invoicing services. See QuickBooks, payments, Shopify, WooCommerce, eBay and Etsy and shipping.
Most business software publishes an API. On the call we read its documentation against the step you want automated before we quote. The same goes for an ERP.
Then we find the next best door. For a recycler in Hungary, the software prepares exactly what the office types into the national waste register. When FedEx only says something by email, our order desk reads the email.
Thirty minutes with us. Show us the two screens your team copies between, and we tell you whether their APIs can do it, what we would build and what it costs.