Create a table of contents

Vellum scans a PDF’s text layer to spot its headings: font size clearly larger than the body text, bold weight, numbering (“1.”, “1.2”, “Article 3”), position near the top of the page. A hierarchy of two or three levels comes out of it, fully editable — rename, change level, delete, add an entry — before being written into the document as clickable bookmarks. An option additionally inserts, at the start of the file, a printed table-of-contents page listing each title with its page number, shifted by however many pages were inserted. Both the analysis and the writing happen entirely in your browser.

How does Vellum detect a PDF’s headings?

The tool looks at the document’s text layer: font size clearly larger than the body text, a bold weight, numbering (“1.”, “1.2”, “Article 3”), and position near the top of the page are combined signals. Since a PDF stores no real structure, this is detection, not reading — check and correct it before saving.

Is the suggested hierarchy always right?

No, and that isn’t the goal: it’s a starting point. Rename an entry, change its level, delete anything that isn’t a heading, add anything that was missed — the list stays fully editable until you save. A document with no clear signal (an unrecognized scan, an unusual layout) starts from an empty list.

What’s the difference with the “Bookmarks & outline” tool?

“Bookmarks & outline” edits a table of contents that already exists, or builds one by hand, entry by entry. “Create a table of contents” automatically detects headings from the document’s content, with the added option of printing a visible contents page at the start of the file.

What does the option to insert a printed contents page do?

On top of the clickable bookmarks in the navigation panel, it adds one or more pages at the start of the document listing each heading with its page number. Those numbers account for the contents pages themselves: an inserted page shifts the numbering of the rest of the document accordingly.

Are the document’s text, images and fonts changed?

No. Only the bookmark tree is rewritten, and the contents page, if enabled, is added without touching the existing content. Processing happens entirely in your browser, with the file never sent to a server.

Vellum — free PDF tools whose processing stays on your device.