// copy
A copy, not live queries
We fetch the data into our own database once and after that only the changes. Fast for you, and well within the package's limits.
service :: integrations
Integrations that
end the retyping.
Your accounting, your till and your web shop each know something the others need. We build the integrations between them. We know Exact Online, MplusKASSA and Nmbrs Accounting from the inside, and any other package with an API can join.
#// what we connect
Three packages, built from the inside
exact-online
Exact Online
Reading purchase invoices, creating items and purchase orders, price lists with margin alerts, stock per warehouse and an order portal.
live at a drinks wholesaler since October 2026
view mpluskassa
MplusKASSA
Till sales to stock and accounting, webhooks on every receipt, the daily journal to your cash book, and one stock level with your web shop.
tested on our test till · weekly export to Exact live
view nmbrs
Nmbrs Accounting
Sales invoices that Nmbrs books and emails, a cash book in the format Nmbrs imports, status per purchase invoice and a payment batch with IBAN check.
built for a café · tested against the real API
view other package
Anything else with an API
SnelStart, WeFact, TimeChimp, Mollie or your web shop: the same approach works for any package with an API.
ask us#// how we build
Writing safely
into your books
An integration that reads can't break anything. One that writes can. That's why we build every integration to the same pattern, whatever the package.
// writes
Named write actions
Writing is only possible through actions agreed up front. A test in the code fails as soon as one is added that wasn't agreed.
// approval
Look first, then book
Every booking shows up front what will happen. Only after a 'checked' tick and a check on the totals does anything go to your books.
// errors
Errors aside, work goes on
An unknown item or a timeout doesn't hold up the rest. It becomes an alert for whoever picks it up, and an interrupted run resumes where it stopped.
#// from practice
drinks wholesaler with a liquor shop
From supplier invoice to Exact, built in a month
Invoices from ten suppliers are read and recalculated, new items and purchase orders go to Exact after approval, price lists get an alert when the margin is too low, hospitality customers order in their own portal and till sales go to the shop warehouse. We leave out the client's name.
10
suppliers with their own reader
97%
of invoices match to the cent
8
named write actions
15 min
between two stock updates
Exact Online running at a clientMplusKASSA tested on our test tillNmbrs Accounting built, in testing
#// from our work
What we learned along the way
1 November 2026·5 min
Eight write actions and no ninth: how our software writes safely to an accounting package
An integration that reads cannot break anything. One that writes can. How we limit writing to Exact Online and Nmbrs: a fixed list, tests that guard the list, look first and then book.
read more31 October 2026·5 min
Beyond invoices: what else you can build on an accounting connection
A connection to Exact Online is almost always built for one thing. That is a waste, because the same connection can tie together your stock, your point of sale and a customer order portal. Four building blocks from our own work.
read more25 October 2026·5 min
Writing to the Exact Online API: what the documentation does not say
Reading from an accounting package is easy. Writing is where it bites. Five things we ran into while creating items in Exact Online that are not in the documentation.
read more20 October 2026·4 min
Asking your accounting system questions from Claude
We built a client a custom connection that lets Claude answer questions about their accounting data. Read only, separated per administration, and with a lesson about how you design such a connection.
read more#// rates
Start small, a fixed price per phase
hourly rate
€90
for small jobs and extensions
day rate
€600
for build days
kickoff
€600
one day, with a plan and a price per phase
All amounts excl. VAT. A fixed price per phase, and the code is yours. Management and monitoring are available for a fixed monthly fee.
#// frequently asked questions
Which packages do you integrate with?
Regulars are Exact Online, MplusKASSA and Nmbrs Accounting (formerly Yuki). We have also built integrations with SnelStart, WeFact, TimeChimp and Mollie. If a package has an API, we can almost always connect to it.
How is this different from Zapier or Make?
A custom integration runs as its own code with its own database, tests and alerts. That pays off when your process has rules, exceptions or bookings. For a simple step from A to B a standard tool may be enough; then we'll say so.
Do my books stay in charge?
Yes. The books stay in your own package. Our integration is the front end and control layer in front of it: input, alerts and checks. Not a replacement for your accounting.
What if the package changes its API?
We see it in the integration's alerts and adjust it. An integration is a service: management and monitoring are available for a fixed monthly fee.
What does an integration cost?
€90 per hour or €600 per day, excl. VAT. We start with a one-day kickoff (€600) and then agree a fixed price per phase.
Who owns the code?
You do. You get the source code in a repository in your name, built with open-source technology, so any developer can continue with it later.
A whole system rather than an integration? See custom software or automation.
$contact --reason="new client"
Can we help
your business?
Digital agency in Groningen for Claude hosting, websites, automation and AI agents that simply do what they should. We handle the tech, you handle the growth.
stats.json
- Experience// years online20y
- Projects// live & running100+
- Tool lock-in// always the best solution0