Documentation
VAMPIRE PHP checks e-invoices directly inside your PHP process. It needs no Java, starts no other program and opens no network connection, so the invoice never leaves your server. This page shows you how to install VAMPIRE PHP and check your first invoice.
What matters
To our knowledge, VAMPIRE PHP is the only tool that runs the official validation rules for e-invoices completely in pure PHP. VAMPIRE JS brings the same rule packages to pure JavaScript. Neither needs Java or an extra process, and the invoice never leaves your system.
Evidence: 220 of 220 invoices for which VAMPIRE and the official KoSIT validator reached the same result, measured on October 9, 2026.
of the invoices for which VAMPIRE PHP and the official KoSIT validator fired exactly the same rules, before and after allowing for one explained difference in the version of the rules
measured on October 7, 2026
invoices for which VAMPIRE and the official KoSIT validator reached the same result
measured on October 9, 2026
comparisons of VAMPIRE JS with VAMPIRE PHP, each one rule set with one invoice, all without a single difference
measured on October 9, 2026
invoices for which VAMPIRE JS and VAMPIRE PHP produced exactly the same validation report
measured on October 9, 2026
VAMPIRE PHP is a validator for e-invoices written in pure PHP. It needs PHP 8.2 or newer with the extensions dom, libxml and bcmath, and it has no other runtime dependencies. This means it also runs on ordinary shared hosting. VAMPIRE PHP is free software under the GPL-2.0-or-later. You install it from Packagist with composer require invoicepress/vampire-php; the individual steps are in the Composer guide.
The following file checks one invoice. It prints "accepted" if the invoice is accepted and "rejected" if it is rejected. The file runs exactly as shown here. Call it in your project folder with php check.php invoice.xml.
<?php // SPDX-License-Identifier: MIT // Checks one e-invoice with VAMPIRE PHP: php check.php invoice.xml // A command-line script: it reads the file name from the command line and refuses to run in a web server. if ( PHP_SAPI !== 'cli' ) exit( 1 ); require __DIR__ . '/vendor/autoload.php'; $vampire = __DIR__ . '/vendor/invoicepress/vampire-php'; $resolver = EinvoiceValidator\Pipeline\ScenarioResolver::fromJsonFile( $vampire . '/rulesets/scenarios.json' ); $result = ( new EinvoiceValidator\Validator( scenarioResolver: $resolver, baseDir: $vampire ) )->validateFile( $argv[1] ); printf( "%s: %s\n", $argv[1], $result->isAccepted() ? 'accepted' : 'rejected' );
The file scenarios.json holds the matching rules. It decides which schema and which rule sets an invoice gets. A rule set holds the validation rules of one format in one version, for example the rules of XRechnung 3.0.2. baseDir is the folder that the paths in this file are resolved against; that is the package folder.
The second example prints every finding one by one. It then writes three reports, each for a different purpose: the JSON report for your own software, a printable HTML page for people, and the report in the format of the KoSIT validator for tools that already read that format. With ruleReport: true, the JSON report also contains the positive validation report, which lists every checked rule with its result on a line of its own.
<?php
// SPDX-License-Identifier: MIT
// Checks one e-invoice with VAMPIRE PHP, prints the findings and writes the reports: php report.php invoice.xml
// report.json the JSON report, with the positive validation report ( every rule with its result )
// report.html a printable page
// report-kosit.xml the report in the format of the KoSIT validator
// A command-line script: it reads the file name from the command line and refuses to run in a web server.
if ( PHP_SAPI !== 'cli' ) exit( 1 );
require __DIR__ . '/vendor/autoload.php';
use EinvoiceValidator\Pipeline\ScenarioResolver;
use EinvoiceValidator\Report\{ HtmlReport, JsonReport, KositXmlReport };
use EinvoiceValidator\Validator;
$vampire = __DIR__ . '/vendor/invoicepress/vampire-php';
$resolver = ScenarioResolver::fromJsonFile( $vampire . '/rulesets/scenarios.json' );
$validator = new Validator( scenarioResolver: $resolver, baseDir: $vampire, ruleReport: true );
$result = $validator->validateFile( $argv[1] );
foreach ( $result->messages() as $message ) {
printf( "%-12s %-14s %s\n", $message->flag->value, $message->ruleId ?? '-', trim( $message->text ) );
}
file_put_contents( 'report.json', ( new JsonReport() )->toJson( $result ) );
file_put_contents( 'report.html', ( new HtmlReport() )->render( $result ) );
file_put_contents( 'report-kosit.xml', ( new KositXmlReport() )->render( $result, (string) file_get_contents( $argv[1] ) ) );
echo $result->isAccepted() ? "accepted\n" : "rejected\n";
exit( $result->isAccepted() ? 0 : 1 );
⚠️ Read the result from isAccepted(), not from the number of errors. The result says whether the invoice is accepted or rejected. The number of errors alone can be misleading in two cases: a rule set may mark a warning as blocking, and an invoice that VAMPIRE could not match to any rule set has no rule findings at all, yet it is still not accepted.
vendor/bin/einvoice-validator validate invoice.xml vendor/bin/einvoice-validator validate invoice.xml --format=json --rule-report vendor/bin/einvoice-validator validate invoice.xml --matrix vendor/bin/einvoice-validator ruleset:list vendor/bin/einvoice-validator selftest
The exit code is 0 for an accepted invoice and 1 for a rejected one. For an invalid call it is 2. This makes it easy to use the check in scripts and pipelines.
With the option --cascade, VAMPIRE checks a ZUGFeRD or Factur-X invoice first against the rules of the newest version and, if it is rejected there, against the rules of the next older one. It stops at the first version under whose rules the invoice is accepted. If no version accepts the invoice, VAMPIRE shows the report of the newest version, because the invoice is then faulty under every version, and the newest one is the authoritative one. The option --matrix, by contrast, checks every version and prints a table with one row per version, so you see the result of every single version.
Do you create your invoices with horstoeko/zugferd or horstoeko/invoicesuite? Then VAMPIRE PHP can check them in the same process, without going through a file. You simply pass the finished document to the validator:
$result = $validator->validateDom( $document->getContentAsDomDocument() );
$document is the document you built with ZugferdDocumentBuilder. $validator is the validator from the first example. If you have the XML as a string, use validateString() instead. You need no extra package for this, because you simply call VAMPIRE PHP in the usual way.
New rule releases arrive as a new version of the package, and the command composer update invoicepress/vampire-php fetches them. The rule packages are free, and there is no subscription for them.
How we measured this is described in the section "How it was measured" at the end of this page. Install VAMPIRE PHP for free with Composer now and check your first invoice.
VAMPIRE PHP and all rule packages are free and available on GitHub and Packagist. You can buy VAMPIRE JS in the shop on invoicePress.de.