A QTSP, or Qualified Trust Service Provider, is an organization recognized under the EU eIDAS framework and listed on an official trusted list. This status is not just branding: it means the provider is authorized to deliver qualified trust services such as certificates, electronic signatures, seals, timestamps, or website authentication.
In cyber security, QTSP status matters because many systems rely on it to decide whether a digital identity, certificate, or signing service should be trusted. Defenders use trusted-list checks to validate certificates and support high-assurance workflows, while attackers may try to imitate or abuse trusted identities to make fraudulent messages, documents, or transactions look legitimate. For that reason, QTSPs sit at the intersection of identity proofing, PKI governance, and auditability. When a system treats a provider as qualified, it should verify that status against the current trusted list rather than assuming it forever.