Ory is the largest open source community in the world for cloud software application security. We maintain advanced open source security software solving authentication, authorization, access control, application network security, and delegation. Ory implements a variety of industry and best-practice standards including OAuth 2.0 / OAuth 2.1, OpenID Connect, Zero Trust Networking, Google Zanzibar Policy Framework, FIDO2 U2F, WebAuthn, TOTP, and more.

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in that case you probably want the plain old redirect based APIs for a custom UI
make sure to read <https://www.ory.sh/docs/kratos/bring-your-own-ui/custom-ui-overview> and <https://www.ory.sh/docs/kratos/bring-your-own-ui/custom-ui-basic-integration>
for checking the session status, there is a simple JSON API <https://www.ory.sh/docs/identities/sign-in/check-session-token-cookie-api>