Sandboxer vs Fly.io Sprites

Fly.io Sprites are persistent Linux microVMs with an always-on HTTPS URL, checkpoints and usage-only billing. Sandboxer differs by keeping processes across stop/resume, preinstalling Docker and nested KVM, and exposing any port. Pick Sprites for very cheap idle-heavy agents on Fly's platform; pick Sandboxer for full-VM workloads and long-lived processes.

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

At a glance

Sandboxer and Fly.io Sprites compared
Capability	Sandboxer	Fly.io Sprites
Isolation	microVM Cloud Hypervisor, its own kernel	microVM (hardware-isolated) Docs describe each Sprite as a dedicated microVM with hardware-level isolation.
Full Linux with root	Ubuntu 24.04, sudo, systemd	Described as full Linux where you can install any tools; root/sudo is not explicitly stated in the pages read.
Docker inside	Preinstalled
Nested virtualization (/dev/kvm)
Pause and resume with memory	Running processes come back	partial After ~30 s idle the VM is suspended with memory frozen and resumes where it stopped (warm); if idle longer it goes cold and in-memory state is dropped.
Fork a sandbox	Copy-on-write disk copy that boots fresh
HTTPS URL per port	Private with a token, or public	partial One HTTPS URL per Sprite routes to its HTTP service (default 8080); private to the org by default, can be made public. Other ports are reachable only through the local sprite proxy.
Longest session	No limit on paid plans Auto-stop is up to 30 days or off	no maximum stated Idle Sprites pause after ~30 s; the Tasks API keeps one active for up to 1 hour per task, renewable.
Billing	Per second, flat rate per size Stopped sandboxes are free	usage-based: CPU time, memory time, storage No compute charge while warm or cold.
GPUs
Self-host or open source
Regions	US East (Virginia) and EU Central (Finland)

= not documented publicly.

Price for one 4 vCPU, 8 GB machine

Sandboxer

$0.036/hour

Flat per-second rate for the default size

Fly.io Sprites

$0.33/hour

4 vCPU × $0.0385/CPU-h + 8 GB × $0.021875/GB-h (storage billed separately at $0.50/GB-month hot)

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

Where Fly.io Sprites is strong

Persistent ext4 filesystem with automatic and manual copy-on-write checkpoints that take about a second without interrupting the Sprite.
No compute charge while idle (warm or cold), so intermittent agents cost little.
Every Sprite gets an always-on HTTPS URL with TLS handled, private to your org by default.
Backed by Fly.io's platform, with official plugins for coding agents.

Where Sandboxer differs

Sprites suspend after about 30 seconds idle and cold sleep drops in-memory state, while Sandboxer stop saves memory and disk so running processes come back on resume.
Sprite compute is billed on measured CPU and memory use; Sandboxer bills per second by machine size with plan dollars returned as machine time.
The HTTPS URL covers a single HTTP service per Sprite; Sandboxer exposes any port as its own HTTPS URL.
Sprites docs do not mention Docker or nested virtualization, both of which Sandboxer provides.

Pick Fly.io Sprites if

You want per-use pricing where idle agents cost close to nothing.
You already run on Fly.io and want a persistent Linux box with checkpoints.
Your workload keeps state on disk and tolerates processes restarting after a sleep.

Pick Sandboxer if

You need processes and RAM to survive a stop and resume.
You need Docker, systemd or nested KVM inside the machine.
You want any port exposed as its own HTTPS URL and coding agents preinstalled.

Sources

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

Other comparisons

Sandboxer vs E2B

Firecracker microVMs with memory-preserving pause and fork, and an open-source stack.

Compare

Sandboxer vs Daytona

Many sandbox classes, from containers to VMs, Windows and GPUs.

Compare

Sandboxer vs Modal

Massive scale and GPUs for short-lived sandboxes, gVisor by default.

Compare

Sandboxer vs Vercel Sandbox

Firecracker microVMs billed on active CPU, inside the Vercel platform.

Compare

All 201 comparisons