How do I open a .otf file?

On Windows use Windows Font Viewer (built in — double-click, then Install); on macOS use Font Book (built in); on Linux use Fonts / GNOME Font Viewer (built in). The modern font format, with support for ligatures, alternates and huge character sets.

Can I convert a .otf file?

Yes. It is usually converted to .ttf, .woff or .woff2, either by exporting from one of the programs listed above or with a format converter.

.otf files

.otf file

OpenType Font

The modern font format, with support for ligatures, alternates and huge character sets.

What opens a .otf file

Windows: Windows Font Viewer (built in — double-click, then Install), FontForge
macOS: Font Book (built in), FontForge
Linux: Fonts / GNOME Font Viewer (built in), Font Manager, FontForge

What a .otf file is

OpenType was developed jointly by Adobe and Microsoft and is now an ISO standard. It can carry TrueType or PostScript outlines and adds advanced typographic features — small caps, real ligatures, stylistic sets — that professional typefaces rely on. Installation is identical to TrueType: double-click and confirm.

Converting it

A .otf file is commonly converted to .ttf, .woff or .woff2. It is a binary format, so a text editor will show unreadable characters rather than its contents.

Details

Extension: .otf
Full name: OpenType Font
Category: Fonts
MIME type: font/otf
Created by: Adobe / Microsoft
Format: Binary

Common questions

How do I open a .otf file?: On Windows use Windows Font Viewer (built in — double-click, then Install); on macOS use Font Book (built in); on Linux use Fonts / GNOME Font Viewer (built in). The modern font format, with support for ligatures, alternates and huge character sets.
What is a .otf file?: OpenType Font. OpenType was developed jointly by Adobe and Microsoft and is now an ISO standard. It can carry TrueType or PostScript outlines and adds advanced typographic features — small caps, real ligatures, stylistic sets — that professional typefaces rely on.
Can I convert a .otf file?: Yes. It is usually converted to .ttf, .woff or .woff2, either by exporting from one of the programs listed above or with a format converter.

.ttf — TrueType Font The font format Apple and Microsoft built in 1991 — double-click to install.
.woff2 — Web Open Font Format 2 The current web font format, roughly 30% smaller than WOFF.
.woff — Web Open Font Format A compressed font wrapper made for downloading into web pages.

Sources

Media Types Registry — IANA
Official vendor product documentation — At One Place

How these figures are compiled and checked