Use it yourself
Software your team will actually want to use.
A genuinely well-designed interface for everyday work — sales, purchasing, production and more. Clear, quick, and none of the usual enterprise grimness.
Run your whole business in one place.
Quotes, invoices, customers, stock and purchasing — all in one clean system that’s actually pleasant to use. No more juggling spreadsheets and half a dozen disconnected apps. Start with the basics today; switch on more as you grow.
Your back office
Everything your daily admin needs.
Less paperwork, more time for your business — from quote to paid, with invoicing, receipts, bank and books in one flow.
Peppol e-invoicing
Included freeMandatory for B2B in Belgium from 1 January 2026, with the rest of the EU to follow. CastlesERP speaks Peppol natively — sending and receiving, out of the box.
- Create and receive invoices
- Scan or forward your receipts
- Automatic bank connection
- A direct line to your accountant
- Follow up unpaid invoices
- Webshop connectors (WooCommerce, Shopify, …)
Right-sized
Simple now, ready when you grow.
Small and light for a one-person business — no bloat, no enterprise price tag, just the parts you use.
And if you’ve got bigger plans, CastlesERP takes on the hard parts as you grow — reliability, EU data-hosting, and the compliance an SMB dreads (GDPR, e-invoicing, NIS2) — so ambition never means switching systems.
Try itModular
Only the parts you need — nothing you don’t.
Choose any business module — sales, purchasing, production, finance and more — and switch it on or off whenever you like. The system stays exactly as big as your business.
Extensions
Shape it around how your business actually works.
Business-domain extensions add the concepts specific to your trade and enrich the data models across every module at once — so those details flow through sales, purchasing and production together, not bolted onto a single screen.
Three ways in
Use it, automate it, or build on it.
Point your AI at it
Hand the busywork to your AI assistant.
CastlesERP works natively with AI assistants over MCP, so an assistant can read and update your ERP directly — always within your exact permissions.
Build on it
Wire your ERP into anything.
Every capability is a documented, versioned API. Connect your webshop, your accountant’s tools, or your own software — no scraping, no lock-in.
One safe engine
One engine, one set of rules.
Whether it’s a person, an AI assistant or another system doing the work, everyone comes in through the same door and follows the same permissions and data-isolation rules. What you can’t do, your AI can’t either — so it stays consistent and safe, however you use it. And your data stays in the EU: we only ever see what you hand us, never your whole mailbox.
Cloud & hosting
All in the cloud, self-hosting available.
CastlesERP runs fully in the cloud, hosted for you on EU infrastructure — nothing to install or maintain. Prefer to run it yourself? Self-hosting is available under an enterprise agreement. Same system, same rules, wherever it runs.