Sandboxer vs Runtime

Runtime (withruntime) offers Firecracker microVM sandboxes that auto-pause after idle while keeping memory and processes, with fork, snapshots, previews and Docker after one command. It differs from Sandboxer in active-CPU billing and open-source SDKs, while Sandboxer ships a full Ubuntu VM with preinstalled agents and nested KVM. Pick Runtime for low metered cost and fork-with-memory; pick Sandboxer for agent tooling and a persistent full VM.

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

At a glance

Sandboxer and Runtime compared
Capability	Sandboxer	Runtime
Isolation	microVM Cloud Hypervisor, its own kernel	Firecracker microVM Own kernel; not containers.
Full Linux with root	Ubuntu 24.04, sudo, systemd	partial sudo available in docs; root not explicitly stated.
Docker inside	Preinstalled	After `sudo enable-docker`; docker run and compose work.
Nested virtualization (/dev/kvm)
Pause and resume with memory	Running processes come back	Auto-pause after 300 s idle keeping memory and processes; running again about 76 ms after a wake request (median, Virginia).
Fork a sandbox	Copy-on-write disk copy that boots fresh	1 to 10 running copies with files, memory and running processes.
HTTPS URL per port	Private with a token, or public	HTTPS preview per port, private by default with token; custom domains and public TCP need kept credit.
Longest session	No limit on paid plans Auto-stop is up to 30 days or off	no limit stated Idle pause configurable 60 s to 86,400 s; persistent: true for paid.
Billing	Per second, flat rate per size Stopped sandboxes are free	per active vCPU-hour + reserved GiB-hour $0.025/vCPU-h, $0.0075/GiB-h; paused storage $0.08/GB-month.
GPUs
Self-host or open source		SDKs, CLI and MCP server are open source; the service is hosted.
Regions	US East (Virginia) and EU Central (Finland)	Virginia named; no list

= not documented publicly.

Price for one 4 vCPU, 8 GB machine

Sandboxer

$0.036/hour

Flat per-second rate for the default size

Runtime

$0.16/hour

4 vCPU × $0.025/h + 8 GiB × $0.0075/h (assumes fully active CPU; excludes disk beyond 10 GiB)

List prices from each provider's pricing page, before free credits, plans and storage. This compares price only.

Where Runtime is strong

Fork copies running sandboxes including memory and processes.
Active-CPU billing and free paused compute.
Open-source SDKs, CLI and MCP server.
Compatibility entry points for E2B, Daytona and Vercel SDKs.

Where Sandboxer differs

Runtime bills only active vCPU while Sandboxer prices fixed sizes by the hour.
Runtime forks carry running processes; Sandboxer forks boot fresh from the disk snapshot.
Runtime docs do not state nested virtualization, GPUs or a region list.

Pick Runtime if

You want fork that keeps running processes.
You are migrating from E2B, Daytona or Vercel SDKs.
You want billing based on CPU actually used.

Pick Sandboxer if

You need a full Ubuntu 24.04 VM with root, systemd, Docker and nested KVM rather than a bare sandbox runtime.
You want coding agents preinstalled in every sandbox and driven through a prompt API with streamed events.
You want a fixed per-size hourly price (default 4 vCPU/8 GB at $0.036/h) with plan dollars returned as machine time.

Sources

Runtime homepage and docs

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

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