High egress is often times a cause of connecting to your database via the public network instead of the private network as you are charged for any public egress, the private network has no such network costs.

As for how to see what service is using large amounts of egress, simply dig into the project metrics found on this page -
https://railway.app/account/usage

Thanks, I can see the projects using large egress, however, I'd like to be able to get a sense if it's due to database connections to Neon or Redis data that's being read/written. We are using a different postgres database provider so those connections would be public. However, $4000 for egress to connect to an external database is astronomically high so I imagine there's a bug.

Can you help us see if it's coming from Redis read/write data or if it's coming from connections to our external database?

Railway doesn't make those kinds of metrics available to the end user yet but you can open your project in question and click the View Cost by Service button to get a better sense of what service is racking up these egress charges.

If you have an app with a high frequency of usage, and it connects to external databases for both Redis and Postgres then it is not out of the realm of possibilities to accumulate such a bill.

Thanks for your help. A $4000/month bill for our app which hosts 1200 users is definitely a non starter. I'll look into to see if I can find exactly what's causing it. If this is the expected bill for this level of usage, we'd definitely need to switch to a cheaper service.

The way to complete eliminate your service to database egress fees going forward would be to run the databases on Railway and connect to them via the private network!