How to use box by Simular with Claude Code
Give Claude Code a cloud desktop with Chrome and a shell. One command adds box by Simular over MCP, so Claude Code can browse, sign in and test your app in a real browser.
box by Simular gives Claude Code a computer of its own in the cloud. It is a Linux desktop with Chrome, a shell and files, added to Claude Code as one remote MCP server. Claude Code can open a real browser, sign in, click through your app and use desktop apps there, while your terminal stays yours. For coding work in a git repo, the box by Simular plugin for Claude Code adds /simular-box:offload, which hands a long session to the box, and /simular-box:back, which brings the commits back. The Quick Start sets up the plugin; adding the server by hand doesn't.
What Claude Code can do with box
- Test your app in a real browser. Claude Code opens your staging site in Chrome on the box, signs up as a new user, clicks through the flow and reports what broke, with screenshots.
- Work on sites behind a login. Sign in once on the box. Claude Code reuses the same signed-in browser next time, so it can reach dashboards and admin panels.
- Use desktop apps, not just the shell. Spreadsheets, file managers and other GUI apps on the box, with several steps run in one call instead of one click at a time.
Set up box in Claude Code
Follow the Quick Start to add box and sign in. To add the server by hand, see Claude Code in the MCP guide.
Try these prompts
- "Use box to open my staging site at <URL> in Chrome, sign up as a new user and list every step that fails, with screenshots."
- "Use box to open GitHub Trending and tell me what today's top 3 repositories do."
- "Use box to log in to <dashboard> with the account already signed in on the box and export last week's numbers to a CSV in ~/reports."
What box adds to Claude Code
| Claude Code on its own | Claude Code + box by Simular | |
|---|---|---|
| Where it works | Your terminal and your machine | Plus its own cloud desktop with Chrome, shell and files |
| Logins | Your local browser profile | Sign in once on the box; it stays signed in for every agent you connect |
| Watching the work | Terminal output | Live view of the box desktop; take control at any time |
FAQ
- Does box use my Claude subscription? Claude Code keeps using your own plan or API key for its model. Model calls made by box's own tools use box credits.
- Is it a sandbox? No. box is a full desktop that Claude Code reaches through one MCP link, with a live view you can take over.
- Which other agents can use the same box? Codex, Cursor, ChatGPT, Claude, Gemini and DeepSeek Harness. They all see the same files and logins.
Troubleshooting
box tools missing, or sign-in not working? See Troubleshooting.
Read next
How to use box by Simular with Codex
Add box by Simular to the Codex app, CLI or IDE extension with one MCP link. Codex gets a cloud Linux desktop with Chrome and a shell it can see and control.
How to use box by Simular with ChatGPT
Add box by Simular to ChatGPT as a custom MCP plugin. ChatGPT gets a cloud desktop with Chrome that stays signed in to your accounts. No terminal needed.