The knowledge your team needs is almost never in one note. It is in a dozen: a setup guide, three meeting notes, a spec, a glossary someone wrote in a hurry. Each one is fine on its own. Together they are a pile, and turning a pile into something a person can read start to finish has always been the part nobody wants to do.

Book Mode is rebuilt, and it starts with the sidebar.

The sidebar is the book now

Everything you used to do by hand-editing a Markdown file now happens in the sidebar:

• Add an existing note, a new note, a note from a template, or an external URL, which fetches the page title for you
• Reorder items by dragging, and move them in and out of sections
• Create a section by dropping one item onto another, and nest sections up to three levels deep
• Break up the book with dividers, and rename anything in place

Every change writes straight back to the book, so there is no source note to open and no page to refresh. If you would rather type than click, # starts a section and --- drops in a divider.

The syntax was the problem

Book Mode has been in HackMD for years, and plenty of people never touched it for a reason we heard over and over: you had to remember the syntax. The structure lived in a Markdown file you edited by hand, and the book you were building was somewhere else, behind a refresh. That is a lot of ceremony for “put these six notes in order.” We would rather people use a feature than memorize it.

What changes depends on how you use books

If you have never made a book, the thing that stopped you is gone. When you create one, you set permissions up front:

• Private for personal research and note organization
• Public View to share curated content for others to read
• Collaborative for meeting agendas, team notes, and shared follow-ups

That choice also sets the default reading mode, and you can have HackMD create a folder to hold the book and the notes you make inside it. Notes that already exist stay where they are.

If you share your books, links now carry the book with them. Readers land inside the book instead of stranded on a single page. And on the Share and Publish tabs, HackMD lists any notes whose permissions are narrower than the book’s and offers to align them in one step. You can uncheck anything you meant to keep locked down, it never blocks you from sharing, and there is an undo if you change your mind.

If you already keep books, nothing changes without your say-so. The first time you open an older book, HackMD asks whether to move it to the new experience or keep it on Classic, and either choice is reversible. One thing worth knowing before you say yes: a book’s structure lives in Markdown, and the new sidebar writes back to it.

Valid structure is headings h1 through h3 plus bulleted links. If your book note also holds paragraphs, tables, quotes, or custom HTML and CSS, those are not carried through once you start editing from the sidebar. HackMD saves a version history checkpoint before that first write, so the original is recoverable.

Open a book and look left

Open any book and look at the sidebar. New books use the new experience straight away, and older books ask you first. A few things worth knowing:

• Editing a book’s structure is desktop only in this release. Reading, navigating, and sharing all work on mobile
• The renderer is a per-book setting, in Book settings under Book experience, where the two options are Neo and Classic
• Switching back to Classic stays available, for any book, at any time

We are not finished with books. The sidebar was the thing standing between people and the feature, so it went first, and what comes next depends a lot on what you build with this one. If you make something good, or if you hit something that annoys you, come tell us in Discord. 💜