How is this different from a full availability grid?

It asks about parts of the day rather than half-hour blocks. For friends picking an evening that is the honest resolution — people don't really know whether 18:30 works, only whether that evening does.

Is it free, and does anyone need an account?

Free to create, free to answer, and no account on either side.

Can people say maybe?

Yes. Yes, maybe and no are all separate, and a maybe counts for less than a yes so the slot everyone can definitely do comes out on top.

How long does the link last?

A season. After that the link stops collecting answers, so an old link pasted back into a chat can't quietly restart a decision.

A free availability grid for a group, without the spreadsheet

The week laid out as days and parts of the day. Tap the slots that could work, send one link, and everyone else taps theirs — no dragging across a grid of half-hour blocks, and nothing to install.

How it works

Tap the slots in the next fortnight that could work for you.
Give it a name so people know what they are answering.
Send the link to the group.
Each person taps yes, maybe or no per slot, and the overlap becomes obvious.

Common questions

How is this different from a full availability grid?: It asks about parts of the day rather than half-hour blocks. For friends picking an evening that is the honest resolution — people don't really know whether 18:30 works, only whether that evening does.
Is it free, and does anyone need an account?: Free to create, free to answer, and no account on either side.
Can people say maybe?: Yes. Yes, maybe and no are all separate, and a maybe counts for less than a yes so the slot everyone can definitely do comes out on top.
How long does the link last?: A season. After that the link stops collecting answers, so an old link pasted back into a chat can't quietly restart a decision.