Hello, I have a small .NET API project running on Fly.io with very minimal usage.
There are only 2 users, and they log in maybe 1-2 times per day.
The maximum data transfer is around 5MB per day.
However, I noticed that after 5-6 days of usage, my dashboard showed a $0.46 usage fee.
My concern is:
If I keep my machine always on (even when idle), will this lead to unexpected charges over time — even though my usage stays extremely low?
Also, as long as I stay within the free tier limits, can I keep using Fly.io forever for free?
Is there any risk that my project might be suspended or shut down in the future even if I stay well under the limits?
Lastly, is there any recommended configuration to minimize resource usage and costs?
You’re paying by compute (per second) rather than per user. Autostop/autostart Machines · Fly Docs
Set up autostop to scale down when your users aren’t active on the site.
Possibly I’m misinterpreting you, but I think you might really be working under a misapprehension overall, . There is no free tier†, and the $5 waiver is just an informal courtesy—not a promise of eternal freebies.
Personally, I wouldn’t be surprised if it was quietly changed in early 2026 (the second anniversary of the removal of the real free tier), to make it accumulate uncollected amounts.
@khuezy’s advice is best: minimize your operating costs as much as you can—and always be prepared to pay the full amount next month (without prior warning).
. There is no free tier†, and the $5 waiver is just an informal courtesy—not a promise of eternal freebies.