Build apps
Developer tools
See your app's addresses, open ports and resource use, and open it in VS Code or Cursor over SSH.
See your app's addresses, open ports and resource use, and open it in VS Code or Cursor over SSH.
Tools → Developer has four pages. Each opens from the list and has a back arrow to return to it.
Addresses shows the preview URL and, once the project is published, the published URL. Each has a copy button. The published URL also has a QR code for opening it on a phone.
On a laptop, the preview address (http://127.0.0.1:…) only works in a browser on that machine, so it has no QR code. Publish the app to open it on other devices. On a server, the preview address works for anyone who can open the project, and it has a QR code too.
Ports lists the programs listening inside the sandbox: address, process name, PID, and what each is used for.
| Port | Used for |
|---|---|
8000 | Your app. The preview shows the app on $PORT. |
8081 | The proxy behind the preview and published URL. |
7681 | The Shell tab. |
2222 | SSH. |
Any other port is inside the sandbox only. If your app listens somewhere else, ask the agent to serve it on $PORT. Click Refresh to read the list again.
Compute shows the sandbox’s CPU and memory limits and what it’s using now, updated every few seconds with a small trend line for each value:
Storage shows how much disk the app uses: the whole workspace, split into its code and its dependencies (node_modules and vendor folders), plus App Storage files and how full the sandbox’s disk is.
SSH lets you work on the app from VS Code, Cursor or a terminal. Your edits land in the sandbox, where the agent and the preview see them.
Open SSH → Keys and click Add SSH key. Paste a public key, like the contents of ~/.ssh/id_ed25519.pub. If you don’t have one yet, run ssh-keygen -t ed25519 in a terminal. The name is optional; it defaults to the key’s comment.
Open SSH → Connect and copy the entry into ~/.ssh/config. It gives the project a host name like onedrop-todo-app-12.
Click Open in VS Code or Open in Cursor (both need the Remote - SSH extension), or run the ssh command shown on the page. You land in /workspace as the sandbox user.
Keys belong to your account, so one key works for all your projects. Adding or deleting a key applies to your running sandboxes right away. The Keys page shows each key’s type and SHA256 fingerprint, the same one ssh-keygen -lf prints. Paste only the public key: the page refuses private keys.
A project’s sandbox accepts only its owner’s keys, never passwords. An admin opening someone else’s project sees the owner’s connection details, but has to use the Shell tab instead.
The SSH port changes when a sandbox is recreated, and each sandbox makes its own host key. Come back to Connect to copy the new entry. The entry turns off host key checks because of this; the address only works on the machine running OneDrop.
127.0.0.1), so Connect explains that it only works there.