WOFF to TTF Converter

WOFF is a wrapper, not an outline format

WOFF 1.0 does not change the font inside it. The W3C Recommendation defines a container: a 44-byte header, a table directory, the font tables themselves, then an optional extended metadata block and an optional private data block. Each font table may be compressed on its own with the zlib compress2() function, and a decoder reverses that table by table. The specification is explicit that a WOFF file holds the same set of tables as the input font and that a user agent decodes it so the font "will display identically to the input font".

So decoding is not an approximation. The outlines, the cmap, the GSUB and GPOS layout tables and the hinting all come back as the font maker left them. What you do not always get is a byte-identical file: the spec requires the table directory be rebuilt in ascending tag order, and any unreferenced padding between tables in the original is discarded during packaging. The table data matches; the file layout may not.

Why "WOFF to TTF" sometimes gives you an OTF

Because WOFF only wraps, what comes out is whatever went in. If the web font was built from a PostScript-outline family, the sfnt inside carries a CFF table and the OTTO version tag, and the honest extension for the decoded file is .otf. Renaming it to .ttf does not break it, since rasterisers dispatch on the tag in the file rather than the name, but it is mislabelled and a strict validator will say so. If you specifically need quadratic glyf outlines, that is a second and genuinely lossy step: see OTF to TTF.

What you get back is the subset, not the family

One thing no decoder can undo is subsetting. Web fonts are usually cut down before they are packaged: the build strips glyphs the site never renders, often drops GSUB and GPOS layout features it does not use, and sometimes removes hinting to save bytes. Decoding the web font returns exactly that subset. If the file you pulled off a site carries 240 glyphs, the family it came from may have had two thousand, and the missing ones are not recoverable from the file you have.

When unwrapping is the right move

• Installing a face locally to proof a design against the exact file a site is serving.
• Opening the font in an editor or an inspector that cannot read WOFF containers.
• Feeding a build step, an engine or a PDF generator that only accepts sfnt input.
• Checking the name and OS/2 tables to find out who made the font and what its embedding bits say.

What it is not good for is recovering a commercial font without paying for it. A subsetted, licence-bound web font is not a substitute for the retail family, and the licence travels with the bytes.

Related font conversions

• WOFF2 to TTF for the newer container.
• TTF to WOFF to package a font back up again.
• TTF to WOFF2 for the format worth serving today.
• OTF to TTF when the decoded file turns out to be CFF-flavoured.
• Format hubs: WOFF, TTF, WOFF2 and OTF.