$re = '/"(?<key>[^"]+)_(?<index>\d)": "?(?<value>[^"]+)(?:"|,)+\s/m';
$str = '[
{
"Kemail": "johan@test.nl",
"KLVorname": "Johan",
"KNachname": "Test",
"KLFirma": "Company 123",
"KLStrasse": "Kalverstraat",
"PosAnz": "1058DC",
"KTelefon": "+31610101010",
"VID": "123456789",
"ArtikelEPreis_1": 853,93,
"ArtikelEPreis_2": "70,64",
"Artikelname_1": "LED Mirror Portau",
"Artikelname_2": "Spaanplaat ruw",
"ArtikelMenge_1": "1",
"ArtikelMenge_2": "3"
}
]';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php