Add FAQ

docs/fern/docs/pages/faq.mdx

@@ -16,6 +16,25 @@ subtitle: Frequently asked questions about Stack
   </Accordion>
 </AccordionGroup>
 
+## Product
+<AccordionGroup>
+  <Accordion title="How do you compare to <X>?">
+    Ask yourself about `<X>`:
+
+    - Is `<X>` open-source?
+    - Is `<X>` developer-friendly, well-documented, and lets you get started in minutes?
+    - Besides authentication, does `<X>` also do authorization and user management (see feature list below)?
+    
+    If you answered "no" to any of these questions, then that's how Stack Auth is different from `<X>`.
+  </Accordion>
+  <Accordion title="Can I use Stack with other JavaScript frameworks, like Astro or Angular?">
+    While you can use any backend framework with Stack, the frontend is tightly integrated with Next.js. If you want to use a different frontend framework, you will have to build the integration ourselves with the client endpoints of our [REST API](/rest-api). Some members of our community have started projects to do this, so you may want to join [our Discord](https://discord.stack-auth.com) to coordinate with them.
+  </Accordion>
+  <Accordion title="Can I use Stack with the Next.js pages router?">
+    Only the Next.js app router is currently supported. However, just like any other unsupported framework, you can use the client endpoints of our [REST API](/rest-api) to build your own integration.
+  </Accordion>
+</AccordionGroup>
+
 ## Other
 <AccordionGroup>
   <Accordion title="How can I contribute?">