> For example, Stack Auth is pretty closely aligned to the Next.js ecosystem

Please for the love of god don't get sucked into the trap of building front end code for frameworks. Make it work with a 5 line static HTML file and a <script> tag, then build wrappers if you think they make sense.

Right now we offer prebuilt pages you can redirect to, as well as SDKs your clientside JavaScript can talk to if you want to reskin. Said SDKs are glorified cURL wrappers, and our prebuilt pages are built using them too.

Prebuilt UIs: https://tesseral.com/docs/features/self-serve-organization-s...

The API they talk to, which you can talk to too: https://tesseral.com/docs/frontend-api-reference/tesseral-fr...