Supabase is an open source Firebase alternative. Start your project with a Postgres database, Authentication, instant APIs, Edge Functions, Realtime subscriptions, and Storage.

Supabase

Hey! Just one question on the billing side for the $25 / mo plan. It says that the additional GB of db size are charged and addition $0.125 per GB. Those $0.125 per GB are per month right? So if I use an additional 10gb of db it would cost me $1.25 more per mo?

Yes, it is per month once you pass the 8gb threshold of DB.  Please note that you have also 100GB of storage for files/etc.

I only use the DB thanks for the confirmation!

Is there a limit? Can a db reach 100gb for example?

Are you building Facebook? 😅 

I will have to contact the team to get an idea of how big can it get in each instance size. But I suspect that you'll be required to move also to a larger instance to handle such a large database.

I'll get back to you once I have an answer.

I got an answer, the team confirmed that you can get 200GB+ database and it will be handled by the system. 

But you'll have to be mindful of the EBS I/O throughput in applications of this size: 
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-optimized.html