ssh base@box.watasu.io

Every cloud has a moment where you almost have a computer. You’ve signed up, you’re reading quickstarts, there’s an SDK to install and an example to paste — and somewhere twelve minutes in, you finally run code on someone else’s machine.

We kept asking: what’s the shortest honest distance between “curious” and “shell”? It turns out it’s three characters, older than the cloud you’re renting: ssh.

$ ssh base@box.watasu.io
(base@box.watasu.io) Watasu API token: ····
watasu · key SHA256:wSVM8g… registered — next time no token needed
watasu · sandbox s-682 · template base:2026-06-24 · team myorg · deadline 60m
user@s-682:/workspace$ python3 -V
Python 3.14.6

That’s the whole thing. No SDK, no agent to install, no config file. The username is the template, the password is the API token you already have (watasu login keeps it in ~/.netrc; watasu token prints it), and after the first connect your SSH key is registered automatically — from then on it’s just ssh, no prompt at all. As far as we can tell, nobody else lets you do this; other sandbox platforms hand you an SDK and wish you luck.

The username is a tiny language

Everything rides in the part before the @:

ssh base@box.watasu.io                  # fresh sandbox, latest build, your team
ssh base:2026-06-14@box.watasu.io       # pin an exact template build
ssh myorg/pipeline@box.watasu.io        # your team's own template
ssh s-682@box.watasu.io                 # back to the same machine
ssh ls@box.watasu.io                    # what can I start? what's running?

And because it’s real ssh, everything your shell already knows still works. One-off commands return real exit codes. Pipes go in and come out:

ssh base@box.watasu.io 'python3 -' < analyze.py        # run a local script inside
ssh s-682@box.watasu.io 'tar czf - /workspace' > out.tgz   # bring the results home
ssh base@box.watasu.io 'make test' && deploy               # CI gating, no plugins

Options travel the ssh-native way too — ssh -o SetEnv="WATASU_TIMEOUT=4h WATASU_MEMORY=4096" base@box.watasu.io — and any other env vars you send land inside the sandbox, like ssh has always done.

Leaving is free, coming back is instant

Yesterday we taught sandboxes to sleep. Today the front door uses it: when you type exit, your sandbox pauses — RAM, processes, the training run you left in a tmux — and the goodbye line tells you the way back:

sandbox s-682 paused · reconnect: ssh s-682@box.watasu.io

Reconnect and the machine continues, scrollback and all. A paused sandbox bills storage only — cents per gigabyte-month — and since Watasu is prepaid, a forgotten exit is a rounding error on your balance, never a surprise on an invoice. Sessions default to a one-hour deadline with pause-on-timeout, so even a dropped connection can’t leave a meter running overnight.

Agents already speak ssh

This is the part we’re most excited about. Every agent framework, every CI system, every cron job, every language written since 1995 can spawn ssh. Which means every one of them can now have a disposable Linux machine with real exit codes and no SDK in the loop:

sshpass -p "$(watasu token)" ssh base@box.watasu.io 'uv run repro.py'

An agent that can run a command can create a machine, use it, and leave it paused for its next step. The integration surface is your operating system.

The boring parts, done properly

It’s still ssh, so trust works the way ssh trust works: one published host key (fingerprint in the docs, SSHFP records in DNS), keys you can list and revoke in the dashboard, and no anonymous mode — a sandbox is always somebody’s sandbox, on a prepaid balance. Sessions negotiate a post-quantum hybrid key exchange (ML-KEM): if your newest OpenSSH has started warning about “store now, decrypt later”, you’ll notice box.watasu.io doesn’t trigger it.

And it’s a door, not a different kind of sandbox — everything you start over ssh shows up in the SDKs, the API, and the dashboard, and everything they start is one ssh s-…@box.watasu.io away from your terminal.

Try it

If you have the CLI, the whole first-time setup is one line:

watasu ssh base

It hands over your token for you, and your SSH key is registered on the way through — so from the second connect on, we’re not even in the loop:

ssh base@box.watasu.io

No CLI on this machine? Plain ssh base@box.watasu.io works from anywhere: paste an API token from the dashboard once, and the same key registration kicks in. The SSH docs cover the full username grammar and options — watasu ssh and watasu token ship in CLI 0.1.7 (brew upgrade watasu).

We think this is the nicest way anyone has ever handed out Linux machines. Tell us what you ssh into — info@watasu.io.