ERP for an engineering office
The system a five-person company runs on. Built after hours.
- ROLE
- Architecture, data model, development — all of it alone
- PERIOD
- 2026
- STATUS
- IN PRODUCTION
A five-person engineering office needed to send Peppol e-invoices by January 2027. That was the trigger. It ended as the system the whole company runs on.
I built it on ERPNext and added a custom application only where the stock core fell short: Slovak building law, design documentation stages, works contracts with milestones, site supervision, the authorised engineer stamp. I left the core untouched so it can still be upgraded painlessly.
I did it after hours, alongside my drafting work. When I left the company, I handed the system over documented well enough that they would not have to go through me. Software only its author can keep alive is not finished work.
WHAT I DID
- 01The trigger — mandatory Peppol e-invoicing from 1 January 2027
- 02Architecture — ERPNext as the core, a thin custom layer. The core is never hacked, so upgrades stay painless
- 03Domain model — design documentation stages under Slovak building law, three service lines
- 04E-invoicing — EN 16931 / UBL, deliberately independent of any single access point
- 05Compliance — VAT, vehicle logbook, cash register, hybrid with an external accountant
- 06Handover — documented so the system does not depend on me