Is the download free?

It comes with a membership. The web editor is free to use without one.

No. It runs a local server and does not need the internet — which is the point of it.

The one matching your operating system and processor. If you are not sure about the processor, the page shows every build for your system rather than guessing — a wrong guess hands you a file that will not start.

Run it on your own machine

One file per machine. It starts a local server, opens the editor in your browser, and keeps your grids in a file next to it. Nothing is sent anywhere.

Why local

Some cells only make sense on your own infrastructure. The shell cell — the one that runs commands — is switched off on Leumas and always will be, because a program a stranger pays ten dollars to write should not be able to run commands on the machine that serves everybody else. On your machine, it is yours to use.

Same grids

A grid is a self-contained document. Download one from here, open it there, and send it back — the format is the same, and so is the editor.

What you need

Nothing. The runtime is inside the file. Pick the build for your machine and run it.

Questions

Is the download free?: It comes with a membership. The web editor is free to use without one.
Does it phone home?: No. It runs a local server and does not need the internet — which is the point of it.
Which one do I pick?: The one matching your operating system and processor. If you are not sure about the processor, the page shows every build for your system rather than guessing — a wrong guess hands you a file that will not start.