About Factisk
Invoicing that does what you expect
Factisk is a web-based invoicing system for Dutch freelancers and small businesses, developed by Ster Software. No superfluous modules, but an administration you can build on.
Principles
A few choices define how Factisk behaves. They are deliberate and we stick to them.
The server is the source of truth
Amounts, VAT, invoice status, numbering, payments and permissions are determined on the server. The interface displays, but never calculates on its own.
No gaps in the numbering
An invoice number is only assigned on finalising, in a sequence per company and per year that is protected against concurrent use.
What has been sent stays fixed
The PDF of a finalised invoice is stored and never changes afterwards. What you have is always what your customer has.
Exact arithmetic
Quantities and amounts are decimals with fixed precision, never floating point. Quantity times price therefore stays exact.
Strictly separated per company
Every query is filtered on the active company. Data of another company does not exist for you, not even through an AI connection.
Open to your assistant
Factisk supports the Model Context Protocol, so AI assistants can work with your administration securely, within the permissions you grant.
Technology
Factisk is built on proven, open technology.
Backend: Django with Django REST Framework, PostgreSQL and WeasyPrint for PDFs.
Frontend: Next.js with TypeScript, Tailwind CSS and shadcn/ui. The interface talks exclusively to the REST API.
Integrations: a REST API with session authentication and an MCP server with OAuth 2.1.
Quality: automated tests for backend and frontend on every change, including a test for concurrent numbering.
Where Factisk stands
Factisk is under active development. The core is done; a number of parts are still on the roadmap.
Available
On the roadmap