Our site is self hosted and made up of 2 distinct app, the first is Invision obviously and the other is an in house app we created ourselves. Because they're on the same domain they can see each others cookies so at the moment I look for the presence of `ips_member_id` on the backend (it gets passed because they're on the same domain remember) and then make an API call to get more member info, but this is a bit flakey and doesn't seem to work in all cases.

I looked at OAuth, but I don't want users to have to log in to both parts of the site seperately obviously .. does anyone else have any ideas about how to approach it?.

Ive moved this to the developers area for you, which would be more suitable for your request

What did you use to develop the internal app? I wrote this post for someone trying to integrate Laravel and InvisionCommunity, you can easily replicate it.

I have been using this integration on my Laravel and Invision portal for 3 years now, and have never found any instability issues.