What Font Extensions Are There? A Guide to Font File Formats

Fonts aren't just visual styles — they're actual files stored on your device or server, and like any file, they come in different formats. The extension at the end of a font file (.ttf, .otf, .woff, etc.) tells your operating system or browser exactly how to read and render that typeface. Understanding what those extensions mean — and why they exist — helps you work more confidently with fonts across design tools, websites, and operating systems.

The Most Common Font File Extensions

There are roughly half a dozen font formats you'll encounter regularly, each developed for different purposes and environments.

.TTF — TrueType Font

TTF is one of the oldest and most widely supported font formats, developed jointly by Apple and Microsoft in the late 1980s. TrueType fonts store glyph outlines using quadratic curves and include hinting instructions that help text render cleanly at small sizes on screen.

TTF files work across Windows, macOS, Linux, iOS, and Android, making them the closest thing to a universal desktop font format. Most operating systems can install and use .ttf files without any additional software.

.OTF — OpenType Font

OTF (OpenType) is the modern evolution of TrueType, developed by Adobe and Microsoft. It supports a significantly larger character set, advanced typographic features like ligatures, alternate glyphs, fractions, and small caps, and can contain either TrueType or PostScript outlines internally.

For designers working in tools like Adobe Illustrator, InDesign, or Figma, .otf is typically preferred because it offers richer typographic control. OTF files are also broadly supported across modern operating systems and most professional software.

.WOFF and .WOFF2 — Web Open Font Format

WOFF and WOFF2 were designed specifically for the web. They're compressed versions of TrueType or OpenType fonts, meaning they deliver the same visual output at a smaller file size — which matters for page load performance.

• .WOFF (Web Open Font Format 1.0) is supported by virtually all modern browsers.
• .WOFF2 uses more efficient compression (Brotli-based) and produces files roughly 30% smaller than WOFF, making it the preferred choice for web delivery today.

These formats are not typically installed on your operating system. They live on web servers and are referenced through CSS @font-face rules. If you're downloading a font to use in a desktop app, WOFF files generally won't work — you'd need the TTF or OTF version.

.EOT — Embedded OpenType

EOT is a Microsoft-developed format designed for Internet Explorer. It's essentially a compressed, rights-managed version of an OpenType font. EOT is largely obsolete — modern browsers dropped support for it, and it's rarely distributed or requested today. You may encounter it in legacy web projects.

.SVG and .SVGZ — SVG Fonts

SVG fonts define glyphs using the SVG vector format. They were briefly used for early iOS compatibility and some legacy browser support. SVG fonts are now deprecated in most modern browsers and rarely used in new projects. They have no meaningful role in current font workflows.

.PFB / .PFM / .AFM — PostScript Type 1

These extensions belong to PostScript Type 1, Adobe's original professional font format from the 1980s. PostScript fonts use two files together (.pfb for the font data, .pfm or .afm for metrics). Type 1 support has been sunset by Adobe and removed from major operating systems as of the early 2020s. If you have legacy .pfb files, converting them to OTF is advisable for continued use.

What Determines Which Extension You Need 🖥️

The "right" font extension isn't universal — it depends on several intersecting variables.

Environment matters most. A font used in a print design workflow has different requirements than one embedded in a mobile app or loaded on a website. Desktop operating systems use TTF and OTF natively. Web projects depend on WOFF2 (and WOFF as a fallback). App development may use TTF or OTF depending on the platform SDK.

Software compatibility varies. Most professional design applications handle both TTF and OTF without issue, but some older or specialized tools may prefer one over the other. Some web font services deliver different format bundles depending on how the font is licensed.

File size and performance. For web use, format choice directly affects load times. WOFF2 compresses significantly better than raw TTF, which is why serving a raw TTF on a website is considered poor practice even when it technically works.

Licensing can be format-specific. Some foundries distribute desktop licenses as OTF/TTF and web licenses as WOFF2 — deliberately. The format you receive may reflect the terms of your license rather than purely technical considerations.

Operating system and version. Older systems may not support every OpenType feature even if they can open the file. Rendering quality can vary across platforms even with the same font file. 🔤

The Gap That Depends on Your Setup

Knowing that .otf supports advanced typographic features is useful information. Knowing whether those features matter — and whether your software, operating system, and workflow will actually expose them — depends entirely on how and where you're working with type. A developer embedding a font in a mobile app, a designer building a brand identity, and someone setting up a personal website all have meaningfully different requirements from the same font file. The format question only gets fully answered once the use case is clear.