How do I organize a novel's chapters in iA Writer?

A folder and numbered files

iA Writer has no idea of a book, only files and folders, so the structure is something you set up in the Library. Give the novel a folder of its own and one Markdown file per chapter inside it. Start each file name with a zero-padded number, as in 01 Arrival.md, and sort the Library by name: the list then reads in story order. Start each file with the chapter title as a # Heading, which also gives you a line in the outline for jumping around inside the file.

Moving a chapter means renumbering. Leaving gaps (10, 20, 30) lets you slot a new chapter in at 15 without renaming everything after it.

Joining the chapters with content blocks

Content blocks are iA Writer's way of pulling one file into another. In the same folder, make a file called something like Book.md, and put each chapter's file name on a line of its own, starting with a slash:

/01 Arrival.md
/02 The Letter.md
/03 Harbor Road.md

Preview shows the whole book assembled, and exporting Book.md to PDF, Word, or HTML includes each chapter's text. To reorder the book, swap lines in that one file; the numbers in the file names matter less from then on. The chapters stay separate files, and you still edit them there; the assembly file only points at them.

One thing trips people up. A block's path is read relative to the file it sits in, so if you move the chapters into a subfolder, the lines need the folder name too, or iA Writer cannot find them. Typing a slash and the first few letters of a file name offers matching files to complete it, which saves spelling the path by hand. iA Writer's own help documents the full syntax, including blocks for images and tables.

In Tabularia

There are no files to number. A chapter is a Chapter Heading inside one continuous manuscript, listed as a row in the Outline, and moving it is a drag of that row rather than a round of renaming. The page is laid out as a book from the start. No assembly file, no preview to switch to.

To bring the chapters over, select all the chapter files at once in the import. Every file turns into one chapter. Their sequence follows the file names, and 2 sorts before 10, so the numbering you already did carries over. Import the chapter files rather than Book.md: Tabularia does not expand content blocks, so the assembly file on its own would arrive as a list of file names. If you would rather bring one file, export Book.md from iA Writer as a Word document and import that.

The trade is plain text. Your chapters stop being Markdown files in a folder you can open in any editor. A Markdown export gives you the text back at any time, as one file rather than a folder, but the working copy lives in Tabularia.