There are many agencies that deliver scuba diving certifications. Most major agencies recognized levels from most of the other ones. Some committees are also formed to ensure equivalence of levels. This allows individuals to start with an agency and continue with another one.
Online validations systems for diving agency
Here are a list of links to the pages or systems for verifying divers and or dive professionals credentials. Agencies are listed in alphabetical order.
IAC – International Aquanautic Club
Divers: https://www.diveiac.de/index.php?id=130
IDEA Europe – International Diving Educators Association
Divers: http://www.idea-europe.eu/database.html
Professionals: http://www.idea-europe.eu/checkpro/check-pro.php
Both: http://www.idea-europe.org/
NADD – NADD Global Diving Agency
Divers: http://mynadd.naddeurope.com/CertificationMember
Professionals: http://mynadd.naddeurope.com/CertificationProfessionalMember
NASE Worldwide – National Academy of Scuba Educators
Divers: http://scuba-training.net/scuba/nase.indexV2.php?szTargetPage=nase.diverStatus.php
NAUI – National Association of Underwater Instructors
Divers: https://www.naui.org/verify-certification/
PSS – Professional Scuba School
Divers: https://www.pssworldwide.org/en/verifyAffiliateCertification.aspx
SDI – Scuba Diving International
Divers: https://www.tdisdi.com/cert-search/
SNSI – Scuba and Nitrox Safety International
Divers: http://scubasnsi.goscubasnsi.com/student-verification/
Professionals: http://scubasnsi.goscubasnsi.com/professional-verification/
Access to the certification and information
Not many agencies are providing this information and with new laws such as the GDPR in Europe, we might see less. For most this data is accessible to professionals affiliated with their respective agencies. Recently most agencies have been providing their divers with certification in an electronic format. Divers can carry their certifications on their mobile devices and can log in the system of the agencies they are certified with.