I'm developing an application where users will want to take information from my app, then feed it through various 3rd party applications. The 3rd party applications all require paid login credentials but are either not set up to, or are unwilling to, allow me to access their API's through my app if my user is a paid subscriber of their service. I want to simply set up an in app browser that can bring up the user's preferred 3rd party sites and lets them login, and passes through the relevant information. In an ideal world, the in app browser would store their auth token from the 3rd party and use it going forward so they don't need to login again.
Are there security concerns I'm missing? Is there a reason to not do this? Thanks for any and all help.