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Sandboxer vs Kernel (onkernel)

Kernel is a cloud browser platform billed per second, with a standby mode that stops charges when a browser is idle. Sandboxer is a different category: each sandbox is a full Ubuntu VM with root, Docker and nested KVM, not a browser instance. Pick Kernel for browser agents; pick Sandboxer when you need a full VM.

Checked against Kernel (onkernel)'s public docs on October 24, 2026. Sources are linked in the table and listed below.

At a glance

Sandboxer and Kernel (onkernel) compared
CapabilitySandboxerKernel (onkernel)
IsolationmicroVM
Cloud Hypervisor, its own kernel
browser instance
Isolation model not described on the pricing page
Full Linux with root
Ubuntu 24.04, sudo, systemd
Not offered; the product is a remote browser driven over CDP/API, not a general machine
Docker inside
Preinstalled
Not offered; the product is a remote browser driven over CDP/API, not a general machine
Nested virtualization (/dev/kvm)
Not offered; the product is a remote browser driven over CDP/API, not a general machine
Pause and resume with memory
Running processes come back
partial
Browsers enter Standby 5 s after last CDP/Live View activity and stop accruing usage; whether process memory is kept is not stated
Fork a sandbox
Copy-on-write disk copy that boots fresh
No VM fork; browser sessions only
HTTPS URL per port
Private with a token, or public
Not offered; the product is a remote browser driven over CDP/API, not a general machine
Longest sessionNo limit on paid plans
Auto-stop is up to 30 days or off
BillingPer second, flat rate per size
Stopped sandboxes are free
per second
Headless $0.0000166667/s; headful $0.0001333336/s; headful+GPU $0.0008000016/s; standby free
GPUspartial
Headful browsers with GPU acceleration are priced; no general GPU machines
Self-host or open source
RegionsUS East (Virginia) and EU Central (Finland)US default; regional browsers on Start-Up and Enterprise

= not documented publicly.

Where Kernel (onkernel) is strong

  • Per-second billing with no charge while a browser is in standby.
  • Browser pools with no usage charge for idle browsers.
  • Headful and GPU-accelerated browser options.
  • Spending caps per organization or project.

Where Sandboxer differs

  • Kernel runs cloud browsers, not general VMs with root, Docker or nested KVM.
  • Pool slots count toward concurrency whether or not used.
  • Regional browsers need the Start-Up plan or higher.

Pick Kernel (onkernel) if

  • You want per-second browser billing with standby between actions.
  • You need GPU-accelerated headful browsers.
  • You want browser pools.

Pick Sandboxer if

  • You need a full Ubuntu 24.04 VM with root, systemd, Docker and nested KVM rather than a browser only.
  • You want stop/resume that brings running processes back, and sandboxes that cost nothing while stopped.
  • You want coding agents (Claude Code, Codex and others) preinstalled and any port exposed as an HTTPS URL.

Sources

Products change. If something here is out of date, email hello@sandboxer.com and we'll fix it. Kernel (onkernel) is a trademark of its owner. Sandboxer is an independent product and is not affiliated with Kernel (onkernel).

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