Hi @greggs
If you’re using our node SDK, the easiest thing to do might be to use the returnTo (the URL to return to after login) login option like this:
app.get('/login', (req, res) => res.oidc.login({ returnTo: '/app' }));
This is documented here https://auth0.github.io/express-openid-connect/interfaces/loginoptions.html
Some examples here https://github.com/auth0/express-openid-connect/blob/master/examples/custom-routes.js
I hope this helps.
Warm regards