Mind maps on a canvas, kept as plain files on your own computer.
Plant as many trees as you like on one board and grow each one as deep as the
idea goes. No account, no cloud, no sign-up. Every board is a .json file in a
folder you can see, copy, back up and read.
1. With the launcher — boards become real files
Start Branchboard.bat
A small console window opens and your browser follows. Every board is saved as
its own .json file in the boards/ folder next to the app. Keep the console
window open while you work.
Needs Node.js. No npm install required for this part —
the launcher uses nothing but Node's own standard library.
2. Open Branchboard.html directly
Double-click it. Works with nothing installed at all, but boards live in the browser's storage instead of as files. That is a browser rule, not a choice: a page opened from your disk is not allowed to write into folders. Use Export now and then to keep a copy.
The app shows you which mode you are in — a green dot beside "Your boards" means it is writing files, grey means browser storage.
On macOS and Linux there is no .bat; run node server.js in the folder.
Double-click Branchboard on phone.bat instead of the usual launcher. It
prints an address like http://192.168.0.6:8777/ — type that into your phone's
browser while the phone is on the same Wi-Fi. Same boards, same files, live.
Windows will probably ask whether to allow Node.js through the firewall. Say yes for Private networks only.
This is deliberately not the default. While it runs, anyone on that network can read and change your boards — there is no password. Use it on your own Wi-Fi, not a cafe's, and close the window when you are done. The normal launcher stays locked to your own computer.
On the phone itself:
- Pinch to zoom, drag to move the canvas
- Tap a box to select it; its note floats up by itself, since there is no hovering on a phone
- Tap it again to type in it
- Drag a box to move it, same as on a desktop
- The bar along the bottom adds a tree, a child or a sibling, which is what the Tab and Enter keys do on a computer
- Moving a board into a folder uses the card's ⋯ → Move to, since dragging a card onto a folder needs a mouse
Structure
- Folders to file boards away, nested as deep as you like. Under the launcher
these are real folders inside
boards/, so a folder you make in the app appears in Explorer and one you make in Explorer appears in the app - Many independent trees on one board, each to any depth
- Branches fan right, left, or both ways from the trunk
- Collapse any branch; it shows a count of what is hidden
- Drag a branch anywhere — past a box's outer edge makes it a child, above or below the middle slots it in as a sibling, and an amber line shows you which. Drop it well clear of everything and it becomes a tree of its own.
- Eight branch colours, inherited down each branch
- Bold, italic, underline and highlight inside the words, and emoji anywhere in the text — on a box and in its note alike
- An emoji and a link pinned to any box, plus a longer note that stays off the canvas. A box with a note carries a small dot; hover it and the note floats up, so you can read the detail without selecting anything
Getting things in
- A picture of a mind map. A photo or a screenshot. Claude reads it into an outline, you check the outline, then it becomes a board. Needs an API key — see below.
- An outline. Paste indented text from anywhere. Indentation is the
structure; a line at the far left starts a new tree. Bullets, numbering and
Markdown
#headings are understood and stripped. - A board file. Any
.jsonexported from Branchboard.
Getting things out
PNG image, Markdown outline, or JSON that imports straight back.
Read aloud
The play button on the panel reads the selected box and its note; the one on the
Note label reads just the note. P does the same from the keyboard, and the box
being read pulses so you can see where you are. It uses the voices already on
your computer, so it costs nothing and works with the internet off.
Pick the voice and speed from the three-dot menu → Reading voice. Your choice is remembered in this browser.
If the list only shows older robotic voices like Microsoft David or Zira, open Branchboard in Microsoft Edge instead. Edge adds hundreds of natural neural voices to the same list at no cost — they need an internet connection, but everything else in Branchboard still works offline. Windows can also install natural voices system-wide under Settings → Time & language → Speech.
Most "read aloud" Chrome extensions will not help here: they read pages themselves rather than lending their voices to other pages. Only an extension that registers as a Chrome TTS engine would show up in the list.
Built to be driven from the keys. Press ? inside a board for the full list.
The mind-map shortcuts follow Whimsical's, so muscle memory carries over.
Tab |
add a child |
Enter |
add a sibling |
Ctrl + Enter |
add a sibling above |
Alt + Enter |
slot a new parent in above |
Ctrl + Alt + ] / [ |
indent / outdent |
M |
new tree |
C or Ctrl + / |
collapse or expand |
Ctrl + C / X / V |
copy, cut, paste a branch |
Ctrl + F |
find in this board |
Shift + 1…8 |
colour the branch |
Ctrl + B / I / U |
bold, italic, underline the selected words |
Ctrl + H |
highlight the selected words |
P |
read the selected box and its note out loud |
Ctrl + E |
drop an emoji into the words |
Shift + X |
pin an emoji to the front of a box |
= - 0 1 2 |
zoom in, out, 100%, fit, fit selection |
Space + drag |
move the canvas |
Styling is stored as Markdown inside the text itself — **bold**, *italic*,
<u>underline</u>, ==highlight== — so the saved .json still reads as words,
the Markdown export needs no conversion, and an outline round-trips unchanged.
A style bar appears over a box while you type in it; the note field in the
panel has the same four buttons.
Copy and paste are worth knowing. Copying a branch puts it on the clipboard as plain indented text, so it pastes into any other app. Pasting an indented list onto a selected box grows the whole sub-tree underneath it.
This one feature talks to the internet. Everything else is local.
- Get a key at console.anthropic.com
- Put it in a file called
apikey.txtin this folder, on its own, nothing else npm installin this folder, to fetch the Anthropic library- Restart the launcher
The key is read by server.js on your machine and sent only to Anthropic. It
never reaches the browser. apikey.txt is in .gitignore.
This is the Anthropic API, billed separately from any Claude.ai subscription — a Pro or Max plan does not include it. Roughly 3–8 US cents per picture.
Without a key everything else still works, and the picture screen hands you a message you can paste into a normal Claude chat alongside your image; paste the reply into the From an outline tab.
Branchboard.html |
the whole app — layout, styling and code in one file |
Start Branchboard.bat |
the Windows launcher |
Branchboard on phone.bat |
the same thing, but reachable from your phone on the same Wi-Fi |
server.js |
reads and writes the board files, and talks to Claude for picture import. Binds to 127.0.0.1 only, so no other machine can reach it |
boards/ |
your mind maps, one .json each, inside whatever folders you make. Not in this repository |
boards/_deleted/ |
deleted boards land here with a date stamp |
boards/ is deliberately ignored by git. It is where your own thinking lives.
The folder has no fixed path — put it anywhere. To back up, copy boards/. To
move one board to another machine, copy its .json into that machine's
boards/ folder, or use Import.
- The typefaces load from Google Fonts. Offline it falls back to your system font and everything still works.
- Tested in Chromium-based browsers. It uses
color-mix()andRangeAPIs that want a reasonably recent browser. - There is no collaboration, no comments and no sharing, on purpose. Adding them would mean a server and accounts, which would undo the thing that makes this useful: your files, your machine.
MIT — see LICENSE.