Concept map from an outline
Write (or paste) an indented outline and out comes a tidy tree diagram, to download as SVG for printing or PNG for pasting. Every indent is a level: it draws exactly what you give it, without deciding anything for you.
How to write the outline
One item per line. Whatever hangs under another item is written indented, with spaces or a tab: it does not matter whether you use two spaces, four or tabs, it measures the step from your own text. Dashes and bullets in front of the items are fine too, so are numbered and lettered lists, and markdown headings (#, ##), which is how an outline usually arrives already written.
What it draws, and what it does not
It draws a tree: every concept hanging from the one it depends on. That is what school needs nine times out of ten, and it is also what can be taken from an outline without inventing anything. A concept map in the strict sense also has labelled relations between different branches («causes», «is made of»), and those cannot be taken from an outline: they would have to be guessed, and a diagram that guesses is worse than no diagram.
For printing and for pasting
SVG is a vector drawing: it scales as much as you like without going blurry, so it is the one for printing, even on A3. PNG is an ordinary image, handy to paste into a presentation or a document, and it comes out at double resolution so it stays clean even when printed small.
If the map comes out too big
A map is not there to hold everything: it is there to let you take it in at a glance. Past four hundred items the tool stops and tells you, instead of turning out a drawing three metres long that can neither be read nor printed. If you get there, the answer is almost always to split it by chapter and make one for each.
All in here, and always the same
The text is not uploaded anywhere: your browser draws the map. And the same outline always gives the same drawing, so you can touch up one line and redo it with no surprises.