Some known users of phase4 are (in alphabetical order):

• A-Cube S.r.l. (IT) - https://acubeapi.com/
• APRO Software Solutions (NL) - https://aprosoftwaresolutions.com/
• BigLedger Sdn Bhd (MY) - https://bigledger.com/
• Billit (BE) - https://www.billit.eu/en-int/
• Bundesrechenzentrum / Federal Computing Center (AT) - https://www.brz.gv.at/
• codecare software GmbH (de) - https://codecare.de/
• compacer GmbH (DE) - https://compacer.com/en/
• Complyance.io (MY) - https://www.complyance.io/
• DE4A (EU project) - http://www.de4a.eu/
• ecosio GmbH (AT) - https://ecosio.com/
• Fitek AS (EE) - https://fitek.com/
• Formware GmbH (DE) - https://www.formware.de/
• GHX LLC (UK) - https://www.ghx.com/
• ixor (BE) - https://www.ixor.be/
• Melasoft GmbH (DE) - https://www.melasoft.com/
• menten GmbH (DE) - https://www.menten.com/
• NTT DATA Business Solutions AG (DE) - https://www.nttdata-solutions.com
• Nymus NV (BE) - https://www.nymus.be
• OpenPeppol AISBL (BE) - https://peppol.org/
• Pagero Group (SE) - https://www.pagero.com/
• Qvalia Group AB (SE) - https://qvalia.com/
• Storecove (Global) - https://www.storecove.com/
• Strands (ES) - https://strands.com/
• stratEDI GmbH (DE) - https://www.stratedi.de/
• T-Systems Multimedia Solutions GmbH (DE) - https://www.t-systems-mms.com
• Telema AS (EE) - https://telema.com/
• TOOP4EU (EU project) - http://toop.eu/
• unifiedpost group (BE) - https://www.unifiedpost.com/

If you are a phase4 user and want to be listed here, write me an email to phase4[at]helger[dot]com