I've developed spa with reactjs, flux (no third-party implementations) and react-router.
How can i make it isomorphic now? For SEO and better performance with initial loading.
There's a lot of resources out there that can help do this. I also took my client only app and made it isomorphic with the help of these resources...
I had a hard time getting mine off the ground but it was definitely worth it! Best of luck.