Linking External App to Member Database

I’m sure this is addressed somewhere but my Google-fu isn’t working well today and I’m not getting any useful results.

I have a WordPress site with MemberPress for annual memberships. We’re having a smartphone app developed that will need to check on member status to determine what content they have access to. Active members are currently indicated with a “Subscriber” role (role is removed once membership expires, until they renew), so this seems like the best avenue to chase.

The app developers are asking about webhook access and I’m a little lost/overwhelmed by what I’m finding, so hoping for a bit of refined direction here. What I DID find seemed to refer specifically to wordpress.com-hosted sites, whereas I have to do something for a self-hosted site.

Ideally the app would fully link to a member’s account; the app will be used to crowdsource certain data which won’t be stored in the user’s account (that goes to a separate catalog) but it would be great if their membership account kept track of what they’ve submitted (we’ve had the idea of rewarding members with significant contributions).

TIA for any leads, ideas, pointers, etc.

The page I need help with: [log in to see the link]