eInvoice Validation Explorer for VAMPIRE

Paid product · WordPress plugin and app · Version 1.1.0 · Explains the validation reports of VAMPIRE PHP and VAMPIRE JS

Understand your VAMPIRE validation report: every message with field, value and spot in the invoice

The eInvoice Validation Explorer for VAMPIRE turns a VAMPIRE validation report into an explanation you can understand. You drop the report, and with a JSON report the validated e-invoice as well. For every finding, the Explorer then tells you which field of the invoice is meant, which value it contains and where that spot is in the invoice.

VAMPIRE validates e-invoices against the official validation rules without Java. The Explorer does not validate anything itself. It explains what VAMPIRE has found. In the plugin this happens on your own website, in the app right in your browser. Together with the free eInvoice Viewer, every finding even appears right below its field in the readable invoice.

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Read the manual

App and plugin

The Validation Explorer for VAMPIRE as an app and as a WordPress plugin

The explorer is available as an app: a folder that you unpack and open with a double click, on your computer, on your intranet or in SharePoint. The app needs no server and no validation engine, because it reads a report that already exists. The report and the invoice never leave your computer. It reads the JSON report with the invoice or the XML report of VAMPIRE PHP and VAMPIRE JS.

The WordPress plugin is the same explorer with the additional functions of a website: you limit the calls per visitor and day, decide from which role it appears, and show the findings right at the fields of the eInvoice Viewer. The plugin requires the free viewer plugin. App and plugin are paid products and carry the same version number.

VAMPIRE has validated, but the report is written for specialists

VAMPIRE validates e-invoices in the XRechnung, ZUGFeRD, Factur-X and Peppol BIS formats. VAMPIRE PHP runs on your web server, VAMPIRE JS runs in JavaScript, on a server with Node.js or right in the browser. As a result you get a validation report with rule identifiers, messages and paths through an XML file.

Which field of the invoice is meant and which value it contains, the report does not tell you in your own words. The JSON report does not even contain the invoice; it only names the locations. Yet in the end all you want is to tell the supplier, the customer or a colleague in one sentence what needs to change on the invoice.

Drop the report, read the explanation

The Explorer reads both report forms of VAMPIRE. It matches every finding to the right field of EN 16931, the European standard that defines which details an e-invoice contains. It shows the value that is actually in the invoice and marks the spot in a view of the invoice, the document view.

1 · Drop the report
You drop the report of VAMPIRE PHP or VAMPIRE JS, as a JSON file or as an XML file in the format of the KoSIT validator.
2 · Add the invoice to a JSON report
The JSON report needs the validated invoice as an XML file in CII or UBL. The XML report carries it, so that single file is enough.
3 · Read the explanation
For every finding you read the plain-language text, the field and its value, and one click takes you to the spot in the invoice.

How the explanation comes about: you drop the report, with the invoice for a JSON report, and read field, value and spot for every finding.

1. Install the viewer and the plugin

The plugin requires the free eInvoice Viewer for PEPPOL & EN16931. Install the viewer first, then upload the ZIP file from the shop to WordPress and activate the plugin. The rule and field catalogs are included, so you do not need to configure anything to get started.

2. Insert the shortcode

You add [spxv_validation_report] to a page. A shortcode is a short placeholder in square brackets that WordPress replaces with the tool.

3. Drop the report

The page has two labeled fields, the upper one for the report and the lower one for the invoice. An XML report is explained right away. With a JSON report the page waits for the invoice and tells you what is still missing.

What makes the Validation Explorer for VAMPIRE special

Both report forms of VAMPIRE

The Explorer reads the JSON report together with the validated invoice, and the XML report in the format of the KoSIT validator, which already contains the invoice. With an XML report, an invoice dropped in addition is ignored, so you always see the document that VAMPIRE actually checked.

What you gain: You use the report your software writes anyway and do not have to convert anything.

The affected field and its actual value

Every finding is matched to its business term of EN 16931, with the BT or BG number. Business Terms (BT) and Business Groups (BG) are the numbered fields and field groups of the standard. If a finding concerns an attachment of the invoice, the Explorer names it, for example “Attachment: Aufmass.pdf”.

What you gain: You see at once which detail the supplier has to change, and you can tell them the wrong value.

What a raw VAMPIRE report shows and what the Validation Explorer adds
	Raw VAMPIRE report	With the Validation Explorer
Result, rule identifier and message	✓	✓
Explanation in plain language	–	✓
Affected field with BT or BG number	–	✓
Value that the invoice contains	–	✓
Jump to the spot in the invoice	–	✓
Finding right below its field in the readable invoice	–	✓

The whole chain without Java

VAMPIRE validates without Java, and the Explorer does not need it either: the plugin runs with WordPress and PHP, the app in a current browser. With VAMPIRE JS and the Explorer app, validation and explanation even stay entirely in the browser.

What you gain: You can run validation and explanation on ordinary web hosting or without any server at all.

No message gets lost

Some messages point to no spot in the invoice, for example because they concern the schema. They appear in the “Not assigned” box at the end, each with its rule identifier, the reason and the path from the report.

What you gain: You see the complete report and can rely on the page saying the same as VAMPIRE, only more clearly.

Search, filter and read in three languages

A search field searches the document view by element name, value or BT number. The “BT numbers” switch shows and hides the numbers, and the “findings only” switch shows only the lines with errors and warnings. The interface is available in German, English and French; German rule texts are available for XRechnung.

What you gain: Even in an invoice with hundreds of lines, a few keystrokes take you to the detail you are looking for.

In the eInvoice Viewer: validate and see the finding at its field

The free eInvoice Viewer for PEPPOL & EN16931 is the central tool for your e-invoices. It displays every invoice in readable form. If the free eInvoice Validator for VAMPIRE is installed on your website, the viewer’s toolbar shows the button “Validate with VAMPIRE”, and the report opens in its own tab, “VAMPIRE Validator”.

With the Validation Explorer for VAMPIRE, the explanations appear right in this tab. A click on “Position” next to a message opens the “INVOICE” tab at the affected field, and there every finding stands right below its field. On the Explorer’s own page, too, the “Invoice” view shows the invoice with every finding at its field as soon as the viewer is active.

To our knowledge, the Validation Explorer is the only tool that shows the messages of a finished validation report at the affected field of the readable invoice. A survey of about 35 tools on October 13, 2026 found no other.

What you gain: Reading, validating and understanding happen on one page, and you see an error where it sits in the invoice.

Go to the eInvoice Viewer

Who the Explorer is for

Accounts payable
An incoming invoice fails with VAMPIRE. The clerk drops the report, reads which field is affected and writes the supplier a query that he will actually understand.
The developer
Her software validates every outgoing invoice with VAMPIRE PHP and stores the JSON report. When VAMPIRE reports an error, she drops the report and the invoice and sees the field of the standard and the value her software wrote.
The service provider
A tax firm or agency validates invoices for its clients with VAMPIRE. Instead of passing on the raw report, it points to a page on its website where the client can have the report explained.
The operator without Java
His web hosting does not run Java. With VAMPIRE and the Explorer he still validates e-invoices and explains the results in full.

The shortcode

[spxv_validation_report]

With the attribute bt you define for a single page whether the BT numbers are visible when a report opens, for example [spxv_validation_report bt="0"] for accounting.

The settings

The settings have their own menu entry, eInvoice Validation Explorer → VAMPIRE, in the WordPress admin area. If the plugin cannot find its rule data, a yellow notice there tells you so.

The plugin settings and their defaults
Setting	Default	What it is for
Daily uploads per role	10 per role	One row for guests and one for each role: empty means unlimited, 0 means no access. Administrators are never limited.
Maximum file size (MB)	8	Applies per file. The upload limit of your server applies as well.
Trust proxy header	off	For websites behind a reverse proxy that you trust.
Show BT numbers by default	on	Visitors can switch the numbers in the report themselves.
Design kit	Kit H	Sets the styling and applies to all eInvoice tools on the website.

For developers

The REST address POST /wp-json/einvoice/v1/explain-vampire accepts the file fields report and invoice and returns the finished view. The manual describes the details.

The report and the invoice stay with you

In the plugin, only on your own website
The report and the invoice go to your WordPress installation, and only there. The plugin makes no request to another server and loads no fonts from outside.
Nothing is kept
The files are read from the temporary upload in memory. They do not end up in the uploads folder or in any log.
In the app, everything stays in the browser
With its default settings the app makes no request at all. The report and the invoice are read in the browser and sent nowhere.
A daily limit without a stored IP address
The plugin counts logged-in users by their account and guests by a hash of their IP address. The counter expires after one day.

Please note: A report and an invoice usually contain names, addresses, bank details and amounts. If you offer the plugin publicly, this data sits in the memory of your server during the request. Mention this in your privacy policy.

What the Explorer deliberately does not do

It does not validate. The result comes from VAMPIRE; the Explorer shows it and explains it.
For a JSON report it needs the invoice. Without it, it still reads the whole report, but the document view stays empty.
It accepts JSON and XML files only. A PDF, even a ZUGFeRD PDF, cannot be dropped.
It is built for VAMPIRE reports. For the KoSIT validator and for Mustang there are separate Explorers.
It neither corrects nor stores anything. It writes no invoice, and there is no archive of earlier reports.
German rule texts are available for XRechnung. For the other rule sets the original English text appears, and the view says so.

Goes well with

eInvoice Validator for VAMPIRE

Validates e-invoices right in WordPress with VAMPIRE PHP, without Java, and shows the report in the same plain-language view. Learn more
free

eInvoice Validation Explorer for KoSIT and for Mustang

The sister tools for the reports of the official KoSIT validator and the Mustang validator. As plugins, all three run side by side. for KoSIT · for Mustang
Paid products

eInvoice Viewer – Extended Profiles

Also explains the rules of ZUGFeRD / Factur-X EXTENDED and EXTENDED-CTC-FR and shows the values of the extension fields. Learn more
Paid product

rule sets are explained by the bundled catalog

8 604

rules with an explanation, from EN 16931 to Peppol BIS

311

fields of EN 16931 are in the field catalog

requests to third-party services

The catalog covers EN 16931 in CII and UBL, XRechnung, Peppol BIS Billing 3, Factur-X EN16931, the French Flux 2 rules and the national adaptations for Portugal, Romania, Croatia, Belgium and Italy. Three more rule sets with 3,190 rules, Factur-X EXTENDED and EXTENDED-CTC-FR, are explained with the “Extended Profiles” add-on.

Frequently asked questions

Does the Explorer validate my invoices?

No. It explains a validation report that VAMPIRE PHP or VAMPIRE JS has already written. If you want to run the validation itself in WordPress, use the free plugin “eInvoice Validator for VAMPIRE”.

Is the report enough, or do I need the invoice too?

That depends on the form. The XML report of VAMPIRE carries the invoice and is enough on its own. The JSON report only names the locations; with it you drop the validated invoice as an XML file.

The Explorer for KoSIT reads VAMPIRE reports too. Why this one?

The Explorer for KoSIT reads the XML reports of VAMPIRE, because they use the format of the KoSIT validator. The JSON report of VAMPIRE PHP and VAMPIRE JS is read only by the Explorer for VAMPIRE.

What do I need to use the plugin?

WordPress 6.0 or newer, PHP 7.4 or newer and the free eInvoice Viewer for PEPPOL & EN16931, because WordPress activates the Explorer only while the viewer is active. You need Java neither for VAMPIRE nor for the Explorer.

Is the Explorer available without WordPress?

Yes. The plugin and the app are one product with the same version number. The app is a folder whose start file you open in your browser with a double-click, on your computer, a network drive or your web server. There you drag the report and the invoice onto one area together, and the app recognizes the report by its content.

Are the report and the invoice stored?

No. In the plugin they are processed only during the request in the memory of your server, in the app only in the browser. Nothing goes to invoicePress or to a third-party service.

What do I see for an invoice in the ZUGFeRD EXTENDED profile?

Without the “Extended Profiles” add-on, a finding on a rule of the extension shows the validator’s identifier and message, and a note says what the add-on would add. With the add-on, these rules are explained and the extension fields appear.

Turn your next VAMPIRE report into an explanation anyone can follow. Buy the Validation Explorer for VAMPIRE in the invoicePress.de shop, place the shortcode on your page or open the app, and see field, value and spot for every finding.

Buy in the shop

Read the manual

Go to the eInvoice Viewer