Authlete by Authlete is a Backend as a Service (BaaS) providing a set of APIs for implementing OAuth 2.0 authorization servers and OpenID Connect identity providers. It supports the latest OAuth/OIDC specifications, enabling service providers to build compliant CIAM infrastructures without implementing and operating them themselves. Authlete operates entirely in the backend, allowing service providers to maintain control over UI/UX aspects like user authentication and consent. It offers flexible deployment options, including shared cloud, dedicated cloud, and on-premises packages, allowing deployment according to the scale and features of CIAM. Authlete's architecture helps financial institutions enable the best Open Finance experience by providing open APIs essential for SaaS companies to expand the usage scenarios of their services. It supports the latest identity and API authorization standards, including FAPI and CIBA, ensuring compliance with security standards crucial for security and interoperability. Authlete's APIs are carefully crafted to focus on the core of OAuth 2.0 / OpenID Connect (OIDC), allowing the building of a complete OAuth/OIDC server or integration with existing components like IAM and API gateways. Authlete manages the protocol steps and issues tokens on the server's behalf, supplying responses for return to the client. It supports various OAuth/OIDC extension specifications, including PKCE, mTLS, DPoP, PAR, RAR, and OAuth 2.0 Security Best Current Practice. Authlete's API is environment agnostic, permitting user authentication and access authorization using any IAM system. It provides functionalities to deploy, implement, and maintain systems that support OAuth and OpenID Connect protocols, including detailed result/error message responses, client ID alias, and properties feature for associating arbitrary properties with access tokens or authorization codes.