Where

Read, write, validate and/or convert electronic invoices using the commandline version (download on the commandline page) or read how to embed the java library in your software.

What

Mustangproject is a open source Java (Jar or Maven) and a command-line tool, and provides a server with a REST API. Mustangproject 2.16.4 was released on 22.04.2025 and supports ZUGFeRD 2.3.2, ZUGFeRD 1, Factur-X 1 as well as UN/CEFACT CII XRechnung 3.0.1.

2.16.4

2025/22/04

Mustangproject version 2.16.4, released April 22nd, 2025, features 16 small corrections, two of which may be potentially security sensitive and fixes a small resource leak. There is a known issue (#764), which may be addressed in 2.17.0, potentially in May, maybe along with an update to support ZF 2.3.3 (i.e. Codelist version 15): The question […]

Mustangserver 1.6.3

2025/07/03

Today, March 7th, 2025 we published a a new version of our e-invoicing REST API, Mustangserver. It brings the benefits of Mustangproject version 2.16.3, e.g. the possibility to specify item based charges and allowances also using JSON, and fixes a potential security as well as a maintenance issue. Existing users already see the 1.6.3 option, […]

2.16.3

2025/03/03

Today, March 3rd, 2025, we released a new version of our open-source e-invoicing library and tool, Mustangproject. This version 2.16.3 mitigates a potential security issue (#685/#725), allows to write invoices using the invoice class without VAT ID (#745) and more. Details: #558 ZUGFeRDInvoiceImporter does not read BankDetails.accountName #686 Item: add BillingSpecifiedPeriod #739 also parse invoiceperiod […]

Mustangserver 1.6.2

2025/27/02

Today, February 27th, 2025 we published a hotfix to our e-invoicing REST API, Mustangserver, fixing an issue in the “detach” endpoint which may cause some invoices not to display embedded factur-x.xml files.

Mustangserver 1.6.1

2025/06/02

Today, February 6th, 2025 we released a new Version of our Software-as-a-Service e-procurement REST API, Mustangserver, fixing minor details like the in rare cases potential incomplete list of invoice attachments.

2.16.2

2025/05/02

Mustangproject 2.16.2 was released today, February 5th, 2025 and features only minor fixes regarding (among others) PDF and invoice attachments, in detail: #705 specifiedLogisticsCharge is not imported #707 invoiceimporter may fail if certain values are not set #708 embedded files cannot be determined #709 ZUGFeRDInvoiceImporter ignored “first” embedded file in list of pdf attachments #607 […]

2.16.1

2025/21/01

Mustang 2.16.1, released today, January 21st, 2025, features some small corrections like #678 some ubl creditnote attributes are not parsed #679 validation of a XR does not ignore whitespace #681 IBAN assigned to invoice sender not recipient on direct debit #689 incorrect element order when both charge reason and reasoncode are specified be able to […]

2.16.0

2025/10/01

Mustangproject, the open-source e-invoicing toolkit, released it’s version 2.16.0 today, January 10th, 2025. This version adds support to parse charges/allowances (#651), allows allowance and charge reasoncodes also on document level (#657), allows multiple invoice referenced documents (#631) and supports a PDF validation report output (#356, using --log-as-pdf, it’s currently not yet documented anywhere). Further fixes […]

Mustangserver 1.6.0

2024/30/12

Today, Monday, December 30th we released a new version of our E-Invoice-Rest-API Mustangserver which supports conversion to and from CII, UBL and FatturaPA based on a open source project called EeISI. Additionally, it now also supports writing embedded files. As usual, Mustangserver 1.6.0 is not yet the default version for all requests but can be […]

2.15.2

2024/19/12

Mustangproject version 2.15.2 was published today, December 19th, 2024, and brought minor improvements in the fields of Parsing #618 import BT-20 correctly import additional referenced documents into invoice/corrected setting of attachments from jackson corrected parseException structure Validation allow 1p0 as potential xmp version number and Writing correcly write charge reason codes also for non-Xrechnung #617 […]

News archive

Features

  • Read, write and validate ZUGFeRD 2/Factur-X, ZUGFeRD 1 and XRechnung
  • Convert PDF/A1 to PDF/A3
  • Embeddable java library based on PDFbox
  • Permissive license (APL2, free for use in commercial and noncommercial applications)
  • The Mustangproject library
    • is available via Maven Central supporting Maven and Gradle
    • can be embedded in your Java software
  • Command line tool
    • Runs on Linux, Mac OS and Windows as of JRE 1.11
    • Add ZUGFeRD XML to PDF
    • Extract ZUGFeRD XML from PDF
    • Convert CII to UBL
    • Migrate ZUGFeRD 1 to 2 (experimental)
    • Convert PDF/A-1 to PDF/A-3
    • Find out how many PDFs are ZUGFeRD
  • Mustang Server
    • Reads, writes and validates ZUGFeRD 2/Factur-X and XRechnung
    • Converts CII to UBL
    • is a OpenAPI/Swagger REST API and uses oAuth
    • Phive-Validation of other formats and UBL
    • Converts any PDF to PDF/A-3

A Mustang Library .net Version is currently in Beta.

Screenshot of Acrobat Adobe PDF Reader showing a ZUGFeRD invoice with open file attachments tab
At the right you see a sample PDF containing Factur-X/ZUGFeRD metadata generated with the Mustang library. If you open it in Adobe Acrobat Reader just click on the paperclip symbol to see the embedded ZUGFeRD XML structure. It has been created using the invoice class. Which you can also use to create a XRechnung.