FusionAuth is a customer identity and access management (CIAM) platform. It handles login and authorisation for the customers of an application and offers multi-factor authentication, passkeys and passwordless login, single sign-on, social login, role-based access control, user registration and webhooks. All functions are available through an API. Developers can self-host FusionAuth, for example with Docker or Kubernetes, including on premises or in an air-gapped network, or use it as a managed service through FusionAuth Cloud.
FusionAuth is a US company and is therefore subject to US law, including the CLOUD Act. The core software is proprietary and covered by the FusionAuth licence; only components such as client libraries and documentation are open source. A free Community plan exists, including for self-hosting. Organisations that self-host decide where the data is located, for example in a European cloud or their own data centre. FusionAuth says deployment is possible in any geography, but its website does not name specific hosting regions for the cloud service.