What is active CPU billing?

Active CPU billing charges for CPU only while your code is using it. Time the sandbox spends waiting, for example on a network call, does not count as CPU time. Memory is billed for the whole run.

Updated Oct 13, 2026

How it changes the bill

An agent often waits: for a model to answer, for a download, for a test server. With active CPU billing those seconds cost memory only. The less the code computes, the further the real cost falls below the list price for a full hour.

How to compare it

The hourly figures on this site assume the CPU is busy the whole time. For a provider with active CPU billing that is the highest the compute cost can be.

Providers with active CPU billing

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Provider

Isolation

vCPU / hr

GiB / hr

Free tier

Max session

GPU

Bunny SandboxIsolated cloud sandboxes for AI agents, run on gVisor.
Isolation
gVisor
vCPU / hr
$0.020
GiB / hr
$0.005
Free tier
Not listed
Max session
Not listed
GPU
Not listed
ixCloud VMs with up to 100 vCPUs, billed by usage.
Isolation
Full VM
vCPU / hr
$0.029
GiB / hr
$0.011
Free tier
Not listed
Max session
Not listed
GPU
Not listed
Oblien WorkspaceHosted microVM workspaces for AI agents.
Isolation
Firecracker
vCPU / hr
$0.030
GiB / hr
$0.008
Free tier
Free tier, no credit card
Max session
Not listed
GPU
No
Fly.io SpritesPersistent Linux computers that sleep when idle.
Isolation
MicroVM
vCPU / hr
$0.039
GiB / hr
$0.022
Free tier
$30 trial credit
Max session
Not listed
GPU
Not listed
DigitalOcean Harness RuntimeManaged microVM sandboxes for AI agents and their code.
Isolation
Firecracker
vCPU / hr
$0.044
GiB / hr
$0.010
Free tier
Not listed
Max session
Not listed
GPU
Not listed
PandaStack SandboxFirecracker microVM sandboxes for AI agents.
Isolation
Firecracker
vCPU / hr
$0.054
GiB / hr
$0.016
Free tier
$5.40 / month
Max session
No limit
GPU
Not listed