OPML for mind maps: what it is and how to use it

OPML is a file format for outlines. If you keep your notes or tasks in an outliner, you can save them as OPML and open them as a mind map elsewhere. This guide explains what you need to know to use it, without going into how the file is built.

What OPML is, in plain terms

An outline is a list where items can be nested under other items. OPML stands for Outline Processor Markup Language, and an OPML file is simply an outline saved so that different apps can read it. Each line of the outline is an item, and items can sit under other items to any depth.

That is the whole idea. The file keeps the text of every item and how the items nest. It does not keep fonts, colours or the position of anything on a canvas, because an outline has none.

Files usually end in .opml, which is the ending the web tools open. If an app offers “Export as OPML” or “Export outline”, that is what you want.

Why use it with mind maps

The shape of an outline and the shape of a mind map are the same tree. The central topic is the root, the main branches are the first level, and the rest nest below. So an outline converts to a map without any translation, and a map converts back to an outline.

The practical benefits are:

• You can write fast in an outliner and review the shape in a map.
• You can send a map to someone who prefers an outline.
• You are not locked into one app, because OPML is a common exchange format that many outliners and note apps can read and write.

Which apps work with it

Support varies from app to app, so check each one before you plan a workflow around it. Many outliners, some note-taking apps and several mind map apps can save OPML, and a good number can read it. Feed readers are another place where you may have met OPML, since they use it to move subscription lists. For mind maps, the thing to look for is “export” or “import” in the file menu with OPML in the format list.

If an app you use does not offer OPML, Markdown is usually an alternative. The Markdown guide covers it.

Open an OPML file as a mind map

The OPML to mind map tool opens an outline in your browser.

1. Choose Open file, or drop the .opml file on the map area.
2. Each item becomes a topic, nested as it was.
3. Edit the map as you like: rename, add and delete topics, or drag branches.
4. Export when you are done.

Files stay on your device. Nothing is uploaded, and files of up to 50 MB open. The tool takes up to 220,000 topics, which is far more than a hand-made outline contains.

Your outline probably has one top item or many. If it has many at the top level, they become siblings in the map. If you want a single centre, add a parent item over them in your outliner first, or rename the central topic once the map opens.

Export OPML from a map

The path also runs the other way. After editing a map in the browser, export OPML to get an outline you can open in any app that reads it. Your topics and notes go across, and so does the nesting. The layout of the map does not.

You can also export a .xmind file, a PNG image or Markdown. A sensible habit is to keep a .xmind file as your main copy and export OPML or Markdown only when you need to hand the structure to a text tool. For a map with no special layout, the plain outline is enough.

What to expect and what to check

Notes. Apps differ in how they treat notes on an outline item. Open a few items after importing and confirm that the detail you care about survived.

Very flat outlines. An outline with hundreds of items at one level makes an unreadable map. Group them into a few headings first.

Special characters. Plain text, accents and emoji generally travel well. If something looks wrong, check the source app’s export settings before blaming the file.

Formatting. Bold, colours and similar styling are not part of an outline in most apps, so do not expect them back after a round trip.

A quick test before committing is to export a small outline with three branches, open it as a map, change something, export OPML again and open it in the original app. If that round trip works, a larger file will too.

OPML or Markdown?

Both are plain outlines. Markdown is easier to read and write by hand. OPML is easier to exchange between outliner and note apps, since they offer it as a menu choice. Pick whichever your tools support. If both work, use Markdown for text you will edit by hand and OPML for moving structure from one app to another.

For deeper detail on how MindmapPal reads its own files, see the file format page. To compare outlines and maps as ways of thinking, read mind map vs outline.