Quba Viewer alternative: open an e-invoice in your browser
Quick answer
Quba Viewer is a free, open-source desktop application from the ZUGFeRD Community: you download and install it, and it displays XRechnung, ZUGFeRD/Factur-X, UBL and Peppol invoices — plus Order-X orders — on Windows, macOS and Linux. BaseInvoice reads and validates the same files as a web page: no download, no install, and the file is parsed in your browser rather than sent anywhere. Choose Quba if you want a permanent offline tool on your machine; choose BaseInvoice if you have one file to open right now, or you can't install software on a work computer.
Last updated 7 September 2026 · Quba Viewer — project site · Quba Viewer — source code (ZUGFeRD Community)
What Quba Viewer is
Quba is an open-source viewer for structured and hybrid e-invoices, produced by the ZUGFeRD Community. It ships as a desktop application for Windows, macOS and Linux (on Linux also via Flatpak) and is free to download.
It displays XRechnung in both syntaxes (CII and UBL), ZUGFeRD and Factur-X PDFs with embedded XML, UBL invoices and credit notes, and Order-X orders. Beyond display it can also validate invoices; the online validation route runs through Mustangserver and requires an account.
What a browser viewer does differently
BaseInvoice runs as a web page. There is nothing to download, nothing to install, and you don't need administrator rights — which is often the deciding factor on a locked-down work machine. It also works on a tablet or phone.
The file never leaves your browser: detection, rendering and validation all run locally, with no upload to a server. Validation covers the EN 16931, XRechnung and Peppol rules, and every error code it reports has its own page explaining which field is affected and how to correct it.
When Quba is the better choice
If you handle e-invoices daily and prefer a fixed tool on your machine that opens without an internet connection, an installed desktop application is more practical.
If you need to view Order-X orders, Quba is the option — BaseInvoice is built for invoices. And if being able to read the source code yourself matters to you, that argues for the open-source project.
Which formats BaseInvoice opens
XRechnung (UBL 2.1 and UN/CEFACT CII), ZUGFeRD and Factur-X (PDF/A-3 with embedded XML), Peppol BIS 3.0, generic UBL 2.1 and generic CII.
The format is detected automatically — you don't need to know it in advance. From there you get a readable rendering of the invoice, a raw-XML toggle, and validation on demand.
Frequently asked questions
Is there an online version of Quba Viewer?▼
Quba ships as a desktop application for Windows, macOS and Linux and has to be installed. If you want to open a file without installing anything, BaseInvoice is an alternative that runs in the browser.
Is Quba Viewer free?▼
Yes. Quba is open source and can be downloaded free of charge for Windows, macOS and Linux from the project site.
Do I have to upload my invoice to BaseInvoice?▼
No. The file is read and validated inside your browser; it is not sent to a server.
Can I open an XRechnung without installing software?▼
Yes. Drop the XML or PDF into the browser — format detection, rendering and validation all run without an install.
Which formats can BaseInvoice display?▼
XRechnung (UBL and CII), ZUGFeRD, Factur-X, Peppol BIS 3.0, UBL 2.1 and UN/CEFACT CII. Order-X orders are not included.
Open your e-invoice now
Drop the XML or hybrid PDF — it's read in your browser, nothing is uploaded.