alt Hacker NewsV2 scales to zero as of last year.
https://aws.amazon.com/blogs/database/introducing-scaling-to...
It only scales down after a period of inactivity though - it’s not pay-per-request like other serverless offerings. DSQL looks to be more cost effective for small projects if you can deal with the deviations from Postgres.
Ah, good to know, I hadn't seen that V2 update. Looks like a min 5m inactivity to auto-pause (i.e., scale to 0), and any connection attempt (valid or not) resumes the DB.