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Sandboxer vs Heroku

Heroku is a platform-as-a-service: you push code or a Docker image and it runs in dynos, with add-ons and pipelines. Dynos are hardened containers with an ephemeral filesystem, not machines you control. Pick Heroku to host a conventional web app; pick Sandboxer when an agent needs a full VM.

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

At a glance

Sandboxer and Heroku compared
CapabilitySandboxerHeroku
IsolationmicroVM
Cloud Hypervisor, its own kernel
OS containers with custom hardening
Some dyno tiers get dedicated compute or networking.
Full Linux with root
Ubuntu 24.04, sudo, systemd
Docker inside
Preinstalled
partial
Deploying Docker images is supported in the Common Runtime; Docker-in-dyno is not described.
Nested virtualization (/dev/kvm)
Pause and resume with memory
Running processes come back
Fork a sandbox
Copy-on-write disk copy that boots fresh
HTTPS URL per port
Private with a token, or public
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
monthly price per dyno
Listed monthly only, e.g. Fir Compute 4CPU-8GB $300/mo.
GPUs
Self-host or open source
RegionsUS East (Virginia) and EU Central (Finland)Ten global regions for Private Spaces
Region lists vary by dyno type.

= not documented publicly.

Price for one 4 vCPU, 8 GB machine

Sandboxer
$0.036/hour
Flat per-second rate for the default size
Heroku
$0.41/hour
Fir Compute 4CPU-8GB at $300/month ÷ 730 h = $0.41/h; requires a Private Space

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

Where Heroku is strong

  • It is a mature PaaS with a one-command deploy flow and add-ons.
  • Dyno sizes go up to 128 GB RAM (Fir) and 126 GB (Cedar).
  • Docker images can be deployed in the Common Runtime.
  • Private and Shield dynos add isolated networking and compliance options.

Where Sandboxer differs

  • Heroku runs stateless app dynos; Sandboxer runs persistent full VMs.
  • Heroku dyno filesystems are discarded on restart; Sandboxer disks persist and stop keeps memory.
  • Heroku is priced monthly per dyno; Sandboxer bills per second.
  • Heroku has no stated nested virtualisation or per-port URLs.

Pick Heroku if

  • You want a managed PaaS for a conventional web app with add-ons.
  • You need Private Spaces or Shield for compliance.
  • You want git-push deploys without managing machines.

Pick Sandboxer if

  • You need a full Ubuntu VM with root, systemd and Docker inside a microVM with its own kernel.
  • You want stop/resume that keeps running processes and memory, and forks from disk snapshots.
  • You want coding agents (Claude Code, Codex and others) preinstalled and driven through a prompt API.

Sources

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

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