A blank grid for solving logic puzzles next to your book — without writing in it, and shared in real time with whoever is playing with you.
Pieces, obstacles, walls and coloured rooms — all drawn by you, copying the scene from your book.
Plenty of puzzle books — mysteries, whodunnits, grid logic problems — ask you to mark hypotheses, rule squares out and keep track of what you already know. The problem is always the same: either you write in the book and spoil the puzzle for the next person, or you scribble on loose sheets that get lost.
This tool is the scratch paper that was missing. You copy the puzzle's scene onto a blank grid — any size, with the obstacles, walls and rooms from the book — and do your reasoning on top of it. The book stays intact, and your thinking is saved.
And because these puzzles are often solved in pairs, the board is shared: two people on different phones see the same grid at the same time, each with their own notes.
Opening the tool creates a private room that is yours alone, identified by a random code in the address. There is no sign-up and no password: that code is the key.
Copy the room link with a button and send it to whoever is playing with you. Anyone who opens that link joins the same board and gets their own profile, with whatever name they choose.
One of you draws the scene from the book — it is shared by everyone. Then each person places their own pieces, marks and notes, without mixing them up with anyone else's. Everything syncs within seconds.
Ctrl+Z and Ctrl+Y on a computer).No. There is no sign-up, no email and no password. You open it and you are using it.
Nothing, and there is no paid tier and no hidden limits. If you find it useful and want to help pay for the hosting, there is a button for that in the tool — but it is entirely optional.
Inside the tool there is a card at the top with your room link and a button to copy it. Send that link to the other person; they open it and land on the same board. It has to be the full link, with the #room= at the end — the tool's plain address always creates a new room.
There is no fixed limit. Everyone who opens the link gets their own profile, with a colour and a name. In practice, two to four is what makes sense for a puzzle.
In a database hosted in the European Union, and also as a copy on your own device so the tool opens quickly and works without a connection. We store no name, no email and nothing that identifies you. The details are in the privacy policy.
Whoever has the room link — and nobody else. The code is random and there is no way to list rooms or to find them by guessing. Keep the link to the people playing with you.
The tool keeps a list of the rooms you have opened on your device and returns to the last one you used. Even so, the link is the only way into a room from another device, so it is worth saving — in your bookmarks, on your phone's home screen, or in a message to yourself.
Yes. After the first visit the tool opens and works offline, keeps everything on the device and syncs when the network comes back. It can also be installed on your phone's home screen, like an app.
It was built with phones in mind — that is where it works best, with the book beside you. It also works on tablets and computers, in the browser, with nothing to install.
Anything solved on a grid: deduction mysteries, logic problems, placement puzzles, room maps. It does not check solutions or give hints — it is smart squared paper, not a game.
The tool and this page are available in English, Portuguese, German, Spanish and Italian. It picks your browser's language on the first visit, and you can change it at any time in the selector at the top.