Sandboxer vs Capy

Capy is a coding-agent product: each cloud thread runs on its own Firecracker VM (Ubuntu 24.04, sudo, Docker) and Capy's agent opens and follows pull requests. Sandboxer sells the VMs themselves, with SSH, nested KVM and stop/resume that keeps running processes, plus an API for your own agents. Pick Capy if you want a finished agent workflow across GitHub, Slack and Linear; pick Sandboxer if you want to build on the machines directly.

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

At a glance

Sandboxer and Capy compared
Capability	Sandboxer	Capy
Isolation	microVM Cloud Hypervisor, its own kernel	Firecracker microVM Each machine is a Firecracker microVM with its own Linux 6.1 kernel.
Full Linux with root	Ubuntu 24.04, sudo, systemd	Ubuntu 24.04 with user `user` and passwordless sudo; kernel modules can't be loaded.
Docker inside	Preinstalled	Docker Engine with Compose and Buildx preinstalled; containers stop when the machine sleeps.
Nested virtualization (/dev/kvm)		No /dev/kvm.
Pause and resume with memory	Running processes come back	Disk survives sleep; memory, processes and connections don't.
Fork a sandbox	Copy-on-write disk copy that boots fresh	partial Snapshots bake the post-setup filesystem into an image new machines boot from; subagents can share the parent's machine or boot a fresh one.
HTTPS URL per port	Private with a token, or public	Ask Capy to expose a port and it publishes a preview URL; anyone with the URL can open it while the machine is awake.
Longest session	No limit on paid plans Auto-stop is up to 30 days or off	sleeps ~2 min after work stops; background commands up to 6 h Keep awake 4h is available; machines asleep for 30 days are deleted.
Billing	Per second, flat rate per size Stopped sandboxes are free	per hour while awake, prorated Paid in Capy credits; sleeping machines cost nothing; each sleep adds a 2-minute wind-down charge. Plans $20/$100/$200-$1,000 a month.
GPUs
Self-host or open source		partial The desktop app (macOS, Windows, Linux) runs threads in a folder on your own computer; the cloud machines are Capy-hosted.
Regions	US East (Virginia) and EU Central (Finland)	US East (New York)

= not documented publicly.

Price for one 4 vCPU, 8 GB machine

Sandboxer

$0.036/hour

Flat per-second rate for the default size

Capy

$0.40/hour

Large machine, 4 vCPU / 16 GB / 64 GB disk, $0.40/h (no 4 vCPU / 8 GB size is sold; Medium is 2 vCPU / 8 GB at $0.20/h)

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

Where Capy is strong

Each machine is a Firecracker microVM with its own kernel, Ubuntu 24.04, passwordless sudo and Docker.
Machines come with a wide preinstalled toolchain and an XFCE desktop with Chrome streamed into the thread.
Sleeping machines cost nothing, and organization members can wake a sleeping machine from its preview URL.
The agent opens pull requests, follows CI and review feedback, and integrates with GitHub, Slack, Linear and Tailscale.

Where Sandboxer differs

Capy is an agent product you prompt; Sandboxer is VM infrastructure with an API, CLI, SDKs and SSH.
Capy machines lose running processes when they sleep; Sandboxer's stop keeps memory and resumes processes.
Capy has no SSH and no /dev/kvm; Sandboxer has both.
Capy's default 4 vCPU size has 16 GB at $0.40/h; Sandboxer's 4 vCPU / 8 GB is $0.036/h.

Pick Capy if

You want a ready-made coding agent that works from GitHub, Slack and Linear and ships pull requests.
You want a streamed desktop with Chrome for the agent to use.
You also want to run the same agent threads on your own computer (desktop app for macOS, Windows and Linux).

Pick Sandboxer if

You want SSH, nested KVM and full control of the VM for your own agent or tooling.
You need long-running processes that survive a stop and resume.
You want lower per-hour machine prices with per-second billing.

Sources

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

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