SMF·CODESANDBOX
Can a prompt replace CodeSandbox?
Developer tools — cloud dev environments
Exhibit tracking slip
Verdict
Running a real browser-based IDE on your own server — code-server behind a private tunnel, a CLI to spin up a new sandbox from a template — is a real weekend build using existing open-source tools. What doesn't come with it is CodeSandbox's actual product: instant templates, disposable cloud VMs, live preview URLs, and real-time collaboration.
Exhibit A — The prompt
Received on30.07.2026Do not build an editor — deploy the real, open-source code-server (VS Code in the browser) on your own VPS, running under a process manager, bound to localhost. Access it only through a private tunnel (Tailscale or an SSH tunnel) — no public exposure, and that's the entire security model, kept deliberately simple. Build a small CLI that creates a new sandbox from a named template folder (a Node starter, a Python starter, a static-site starter), runs its install step, and prints the URL to open it. Give each sandbox's dev server its own port reachable through the same tunnel, with a small index page listing active sandboxes and their ports. Add a command to archive and remove a sandbox, tarring it before deleting.
Do not build multi-user collaboration, instant VM forking, or public preview URLs — those need real multi-tenant infrastructure, which is exactly what the hosted product provides and a personal server shouldn't attempt to replicate.Opening prefills the prompt — press enter to run it.
Exhibit B — What you lose
- B.1 instant, disposable cloud sandboxes
- B.2 public preview URLs for sharing a running app
- B.3 real-time collaboration
- B.4 managed infrastructure
Prior art
Exhibit C — Why people still pay: cloud platform/collaboration
People pay to avoid managing dev machines just for quick experiments and previews — spinning up and tearing down environments on demand is the actual convenience, not the editor itself.
Questions
Can I import my existing CodeSandbox projects?
Yes, largely — CodeSandbox projects are just code, downloadable as a zip, which drops straight into a new sandbox folder here. Live collaboration state and sandbox forking history don't carry over, since those are platform-specific.
Will it work on my phone?
A code editor in a browser tab technically loads on a phone, but real editing needs a keyboard — this is a desktop tool in practice.
What does it cost to run?
One VPS, typically five to ten dollars a month depending on how much you run at once — no per-sandbox or per-hour pricing.
What's the one thing that doesn't survive the rebuild?
Instant, shareable preview URLs. CodeSandbox gives every sandbox a public URL you can hand to anyone in seconds; here, previews stay behind your private tunnel, which is more secure but means nothing is casually shareable.
Related tools
Receipt