CapabilitiesReaching it
Private link
A link only you or people with a token or login can open.
Short answer: 11 of 16 providers offer it fully: Agent 37, Blaxel, Boat, Daytona, InstaBox, Lizard, Modal, Runtime, Sandboxer, Sprites and Tensorlake. With a catch: Cloudflare Sandbox. Checked 29 October 2026.
Who offers it
Part of Reaching it: links, ports and who can open them, which explains why it matters.
Fully: Agent 37, Blaxel, Boat, Daytona, InstaBox, Lizard, Modal, Runtime, Sandboxer, Sprites and Tensorlake. With a catch: Cloudflare Sandbox. Not at all: boxd, E2B and Vercel Sandbox.
The default address needs your key on every request, or a time-limited signed link.
docs-confirmed “Instance URLs require auth on every request” Source
A private preview needs its token as part of the link or in a request header.
docs-confirmed “When you create a private preview URL a token is required to access the URL.” Source
The link carries a token; anyone without it is refused.
docs-confirmed “To get a URL without a token, add `--public`” Source
The link needs a token unless the machine is marked public; signed links can be limited to one port and one hour.
docs-confirmed “Otherwise, authentication is required.” Source
A private port answers only requests that carry its token, and the token can be replaced.
docs-confirmed “A **private** port answers only requests that carry its token.” Source
One token opens every exposed port on the machine, so a link to one app also opens the rest.
docs-confirmed “A preview URL gives a port inside a sandbox on Lizard a private HTTPS address.” Source
Nothing answers until a port is exposed, and a web request then needs a token you generate.
docs-confirmed “You can make authenticated HTTP and WebSocket requests to a Sandbox by generating Sandbox Connect Tokens.” Source
The link is private with a token by default, and the token can be rotated.
docs-confirmed “It is private, with a token, by default.” Source
Private is the default and the link carries a token that the provider strips before your app sees it.
docs-confirmed “Treat a private URL like a password” Source
The address is limited to your organisation and needs an organisation token from outside it.
docs-confirmed “A Sprite URL is private by default. It's reachable only by members of your org, through the browser or with an org token” Source
Requests need your project key unless you deliberately open the port.
docs-confirmed “Authenticated routing is the default model for sandbox access.” Source
The catch: You have to write the login check in your own small program; the machine brings no token or password of its own.
docs-confirmed “When your Worker forwards a page from a sandbox, the page runs under the hostname that served it.” Source
- boxdNo
Note: Every machine address is open to the internet, and the provider offers no token or login to put in front of it.
inferred “Every machine gets an HTTPS domain automatically.” Source
- E2BNo
Note: There is no built-in lock: anyone who has the link can open it.
docs-confirmed “By default, a sandbox's public URLs are reachable by anyone who knows them.” Source
Note: An exposed port is open to anyone with the link; there is no token or login in front of it.
docs-confirmed “Exposed ports are accessible via a public URL, so be mindful of what services you run.” Source
- MorphNot published
An HTTP service can be exposed, but whether the link is locked by default is not published.
inferred “Expose Http Service” Source
Related
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