Replace one font family with another throughout a document — the CLI equivalent of Word’s Home → Replace → Replace Fonts. Replaces every content-level reference in one pass; theme font references are untouched (use uniword theme fonts for those).

1. Subcommands

Subcommand Description

replace INPUT OUTPUT

Replace a font family throughout a document

2. replace

Replace one font family with another across every place a font name appears in the body content, styles and defaults, headers/footers, footnotes, endnotes, comments, and numbering definitions.

# Swap Calibri for Carlito (Calibri-metric OFL substitute)
uniword fonts replace input.docx output.docx --from Calibri --to Carlito

# Replace Arial with Liberation Sans
uniword fonts replace input.docx output.docx --from Arial --to "Liberation Sans"

Options:

--from

Font family to replace (exact, case-sensitive match; required)

--to

Replacement font family (required)

--verbose, -v

Verbose output

The command prints the total number of references rewritten.

This command rewrites content-level fonts. To replace the theme’s major/minor fonts (Word’s Design → Fonts gallery), use:

uniword theme fonts input.docx output.docx --name carlito_sans

3. Where replacement applies

fonts replace walks every part that can carry a font reference:

Part What is rewritten

word/styles.xml

rFonts in style definitions and docDefaults

word/document.xml

Run-level rFonts in the body

word/header*.xml, word/footer*.xml

Run-level rFonts in headers and footers

word/footnotes.xml, word/endnotes.xml

Run-level rFonts in notes

word/comments.xml

Run-level rFonts in comments

word/numbering.xml

Run-level rFonts in numbering definitions

Theme font references (<a:latin> / <a:cs> in word/theme/theme1.xml) are deliberately left alone so the document’s font scheme stays coherent.

4. Ruby API 

doc = Uniword::DocumentFactory.from_file("input.docx")
count = doc.replace_font(from: "Calibri", to: "Carlito")
puts "rewrote #{count} references"
doc.save("output.docx")