Sales invoices from your own app
You draft the invoice in your own app, with your own layout. On sending, Nmbrs books it and emails it to your customer. Paid or open is read back from Nmbrs.
integration :: nmbrs
Nmbrs Accounting,
with your own app in front.
Yuki has been called Nmbrs Accounting since 1 September 2026; the API stayed the same. We build apps for it that make the work around your books lighter, while the bookkeeping stays in Nmbrs: sales invoices, cash book, purchase invoices and payments. Built for a café and tested against the real API.
✓ built for a café · tested against the real API
#// what we build
What an integration with Nmbrs Accounting does for you
Each part shows how far along it is: running at a client, built and in testing, or proven on our own test setup.
Weekly cash book
The cash book the way you're used to it, with an export in exactly the format Nmbrs imports. Equal to the cash balance in Nmbrs to the cent.
Status per purchase invoice
Per document in the purchase folder: received, booked and open, or settled. If an invoice sits unprocessed for more than a week, you get an alert.
Delivering purchase invoices
Put files in the Nmbrs purchase folder, with a check for duplicate invoices. Nmbrs then recognises and books them itself.
Payment batch for the bank
Open purchase invoices in one SEPA file for your bank, blocked if a supplier's IBAN suddenly differs from the previous payment.
Questions to your books
Balances, cash per week, open items and the original invoice PDF, fetched from Nmbrs. Read-only.
2
write actions: process invoice, deliver document
1,000
calls per day, login counts too
7 days
until an alert on unprocessed purchases
0
new mail servers needed: Nmbrs sends
#// what the docs don't say
Lessons from real work
With an integration you mostly pay for what isn't in the manual. This is what we ran into, so you don't have to.
A typo gives no error
Write a parameter with the wrong capital and the API ignores it and returns an empty result. The spelling also differs per service.
Own PDF only when booking right away
If you send your own invoice PDF, the invoice must be processed immediately too. Otherwise Nmbrs rejects the whole invoice.
Let the package do what it already does
Nmbrs emails invoices and recognises purchase invoices itself. We removed our own mail feature again after three days.
The package picks the contra account
In a cash book import, the transaction code decides which account Nmbrs books to, not the column in your file.
#// how we build
Look first, then book
// 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.
// 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 our work
More on Nmbrs Accounting
#// 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
Does this still work now that Yuki is called Nmbrs Accounting?
Yes. Yuki has been called Nmbrs Accounting since 1 September 2026, but the API hasn't changed: the same services at the same address. Existing integrations keep working.
Why a separate app and not everything in Nmbrs?
What Nmbrs does well, we leave in Nmbrs: emailing invoices and recognising purchase invoices. We build what sits in front: your way of working, alerts, checks and a screen that fits how you work. The books stay in Nmbrs.
Can the app book something by accident?
There are two named write actions: processing a sales invoice and putting a document in the purchase folder. Both require approval, and a test in the code fails as soon as a write action is added that wasn't agreed.
How many calls can an integration make?
Nmbrs allows 1,000 calls per day per domain, logins included. We keep answers for fifteen minutes, so even a busy day stays well within that limit.
Does it get in my bookkeeper's way?
No, if anything it's less work. Invoices and cash books arrive neatly and on time, and alerts about unprocessed purchases or changed IBANs are useful for the bookkeeper too.
What does an Nmbrs integration cost?
€90 per hour or €600 per day, excl. VAT. We start with a one-day kickoff and then agree a fixed price per phase.
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stats.json
- Experience// years online20y
- Projects// live & running100+
- Tool lock-in// always the best solution0