OTF File Format (.otf)
An OTF file stores a font's glyph outlines as PostScript-style cubic Bezier curves, along with the OpenType layout tables that drive ligatures and other typographic substitutions.
OTF at a glance#
| Full name | OpenType Font |
|---|---|
| File extension | .otf |
| Category | Fonts |
| Developer | Microsoft and Adobe |
| First released | 1996 |
| MIME types | font/otfapplication/x-font-otf |
| Compression | Uncompressed |
| Specification | OpenType Specification |
| FileFlip support | FileFlip reads this format but does not write it |
What a .otf file can hold#
These are the things a OTF file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Embedded metadata | Yes |
|---|
Strengths and limitations of OTF#
What OTF does well
- Cubic Bezier outlines describe complex curves with fewer control points than TrueType's quadratic ones
- OpenType layout tables enable ligatures, small caps and per-language glyph substitution that TrueType alone doesn't support
- One format works across macOS, Windows and Linux design and publishing software
Where OTF falls short
- This converter can read OTF but can't write it, so OTF only works here as a source format, not a target
- Not compressed, so serving it directly on the web is slower than WOFF or WOFF2
- Fewer glyph-editing tools handle CFF outlines as completely as they handle TrueType outlines
Use OTF for a font that relies on OpenType features like ligatures or stylistic alternates, which professional design and publishing software reads natively.
Convert OTF to WOFF2 before using it on a website, since browsers need a compressed web font format and OTF isn't one.
How to open a .otf file#
A .otf file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts OTF into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | Windows Font Viewer, FontForge |
| macOS | Font Book, FontForge |
| Linux | GNOME Font Viewer, FontForge |
| Web | FileFlip |
OTF questions people ask#
What's the difference between OTF and TTF?
OTF adds an option for PostScript-style cubic Bezier outlines and OpenType's layout tables, like ligatures and language-specific substitutions, on top of the same font structure TTF uses. A TTF file can't hold those layout features; an OTF file can, whether its outlines are cubic or the same quadratic type TTF uses.
Can OTF fonts be converted back from other formats?
Not with every tool. Some font converters, including this one, can read an OTF file and write it out as TTF, WOFF or WOFF2, but can't write a new OTF file, because reconstructing CFF cubic outlines from a different source isn't supported by every font engine. Turning a WOFF or TTF file into a genuine OTF usually needs a dedicated font editor instead.
Does converting OTF to another format change its license?
No, and it doesn't grant new permissions either. A font's license governs how it can be used and distributed regardless of which container format it's stored in, so a font licensed for desktop use only doesn't become licensed for web embedding just because it was converted to WOFF2.
Converting OTF files#
Convert OTF to another format
FileFlip does not write .otf files, so nothing on the site converts into this format. It works as a source only.
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.