OTF vs EOT: Universal Standard vs Obsolete Format
Comprehensive comparison of OTF and EOT formats covering universal cross-platform font versus obsolete IE-only web font, platform compatibility, and why OTF is the modern choice
In Simple Terms
EOT is obsolete with 0% browser support (IE11 retired 2022). OTF is the universal desktop standard working on all platforms (Windows, Mac, Linux).Use OTF for desktop font installation and as source files. OTF works everywhere, EOT works nowhere—never use EOT in any project.For web: Convert OTF to WOFF2 (68% smaller, 97%+ support). Delete all EOT files—they're completely obsolete and have no modern use case.
In this article
OTF (OpenType Font) and EOT (Embedded OpenType) represent opposite ends of the font format spectrum: OTF is a universal, cross-platform standard succeeding everywhere while EOT was Microsoft's failed proprietary web font achieving nowhere. OTF, developed jointly by Adobe and Microsoft in 1996, combines TrueType and PostScript outlines into a single format that works seamlessly on Windows, macOS, Linux, mobile platforms, and modern web browsers when converted to WOFF2/WOFF—making it the industry standard with near-universal adoption. EOT, created by Microsoft in 1997 exclusively for Internet Explorer 4, was a compressed web font format with DRM restrictions that only IE supported, and since IE11's retirement in June 2022, EOT has 0% browser support and is completely obsolete.
The critical distinction is that OTF represents open collaboration succeeding while EOT represents proprietary lock-in failing: OTF works everywhere because Adobe and Microsoft designed it as an open standard adopted by all platforms, while EOT works nowhere because other browsers rejected Microsoft's IE-exclusive approach with DRM features. As of 2025, OTF is the recommended format for desktop font installation on all operating systems, serves as the source format for generating WOFF2/WOFF web fonts, supports advanced typography features like ligatures and contextual alternates, and provides the best font quality with both TrueType and PostScript outline support. Meanwhile, EOT has zero use cases—it cannot be installed on desktops, no browsers support it for web delivery, and every EOT file should be deleted and replaced with WOFF2/WOFF for web or kept as OTF for desktop.
This guide compares OTF and EOT to clarify why OTF is the universal standard while EOT is obsolete. You'll learn the technical specifications showing OTF's open cross-platform design versus EOT's proprietary IE-only structure, use cases demonstrating OTF's versatility versus EOT's complete obsolescence, platform compatibility proving OTF works everywhere while EOT works nowhere, historical context explaining how open standards defeated proprietary lock-in, and definitive recommendations to use OTF for desktop and convert to WOFF2/WOFF for web while removing all EOT files. Whether managing font libraries, building websites, or modernizing legacy projects, this guide provides essential knowledge about the triumph of open standards over platform-specific technologies.
Format Overview
OTF (OpenType Font)
History and Purpose:
- • Developed by Adobe and Microsoft jointly (1996)
- • Open standard, cross-platform compatibility
- • Designed for universal desktop and web use
- • Adopted by all major platforms and browsers
- • Industry Standard: Near-universal adoption
Technical Characteristics:
- • Supports TrueType and PostScript outlines
- • Advanced typography features (ligatures, alternates)
- • Uncompressed desktop format
- • File size: ~80-200 KB (typical)
- • Extension: .otf
Current Status (2025):
- • Universal desktop format
- • Works on Windows, macOS, Linux, mobile
- • Source format for WOFF2/WOFF web conversion
- • Use case: Desktop installation, web source
EOT (Embedded OpenType)
History and Purpose:
- • Created by Microsoft exclusively (1997, IE4)
- • Proprietary web font format with DRM
- • Designed for web delivery (IE only)
- • Never adopted by other browsers
- • Obsolete: IE retired June 2022 (0% support)
Technical Characteristics:
- • MicroType Express compression (~40-50%)
- • Binary format with DRM/URL binding
- • Limited typography features
- • File size: ~80 KB (compressed)
- • Extension: .eot
Current Status (2025):
- • Zero browser support (0%)
- • Cannot be installed on any desktop OS
- • Completely obsolete
- • Use case: None (delete immediately)
Open Standard vs Proprietary Lock-in
- OTF: Open standard by Adobe + Microsoft, universal platform adoption
- EOT: Proprietary Microsoft format, rejected by all other browsers
- Result: OTF succeeded through collaboration, EOT failed through isolation
- Modern usage: OTF everywhere, EOT nowhere (0% support)
Technical Differences
Side-by-Side Comparison
| Feature | OTF | EOT |
|---|---|---|
| Creator | Adobe + Microsoft (1996) | Microsoft only (1997) |
| Standard Type | Open standard | Proprietary |
| Purpose | Desktop + web source | Web only (IE) |
| Outline Format | TrueType + PostScript | TrueType only |
| Compression | None (uncompressed) | MicroType Express (~40-50%) |
| File Size | ~80-200 KB | ~80 KB |
| Typography Features | Advanced (ligatures, alternates, etc.) | Limited |
| DRM Features | None | URL binding, encryption |
| Desktop Install | All platforms | No |
| Web Compatible | Via WOFF2/WOFF conversion | Was (IE), now 0% |
| Cross-Platform | Yes (universal) | No (IE only) |
| Status | Industry standard | Obsolete (0%) |
OTF: Universal Success
- Open collaboration: Adobe + Microsoft co-developed
- Universal adoption: Windows, macOS, Linux, mobile all support
- Rich features: Advanced typography, ligatures, alternates
- Flexible outlines: Supports both TrueType and PostScript
- Web ready: Converts cleanly to WOFF2/WOFF for modern browsers
- Result: Industry standard, works everywhere
EOT: Proprietary Failure
- Single-vendor: Microsoft only, no collaboration
- IE exclusive: Chrome, Firefox, Safari never implemented
- DRM restrictions: URL binding broke legitimate use cases
- Limited features: Basic typography only
- No desktop use: Web-only, cannot install
- Result: Complete failure, 0% support since IE11 retired (2022)
Use Cases and Context
OTF: Universal Application
- • Desktop installation: Install on Windows, macOS, Linux for use in design software
- • Web source format: Convert to WOFF2/WOFF for web font delivery
- • Typography projects: Full access to ligatures, alternates, advanced features
- • Font development: Industry-standard format for font creation
- • Print design: High-quality PostScript output for professional printing
- • Mobile apps: Embed in iOS and Android applications
EOT: Zero Use Cases
- • No browser support: 0% coverage since IE11 retired (June 2022)
- • No desktop use: Cannot be installed on any OS
- • No development use: Cannot create new fonts in EOT format
- • Historical only: May appear in legacy IE-era websites
- • Action required: Delete all EOT files, remove from CSS
Migration Path: EOT → OTF/WOFF2
- • Step 1: Identify source OTF/TTF files (EOT was generated from these)
- • Step 2: For desktop: Use OTF/TTF directly
- • Step 3: For web: Convert OTF/TTF to WOFF2 + WOFF
- • Step 4: Update CSS to use WOFF2/WOFF instead of EOT
- • Step 5: Delete all .eot files and EOT references
- • Result: Modern, universal font delivery
Platform Compatibility
Platform Support Matrix
| Platform | OTF | EOT |
|---|---|---|
| Windows Desktop | ✓ | ✗ |
| macOS Desktop | ✓ | ✗ |
| Linux Desktop | ✓ | ✗ |
| Chrome (Web) | Via WOFF2/WOFF | ✗ (0%) |
| Firefox (Web) | Via WOFF2/WOFF | ✗ (0%) |
| Safari (Web) | Via WOFF2/WOFF | ✗ (0%) |
| Edge (Web) | Via WOFF2/WOFF | ✗ (0%) |
| iOS/Android | ✓ | ✗ |
| Adobe CC Apps | ✓ | ✗ |
| Microsoft Office | ✓ | ✗ |
✓ = Supported | ✗ = Not supported | Via WOFF2/WOFF = Requires conversion
Important Notes
- OTF for desktop: Install directly on all operating systems
- OTF for web: Convert to WOFF2/WOFF for browser compatibility
- EOT obsolete: Zero platform support as of 2025
- Modern workflow: OTF → WOFF2/WOFF conversion for web
Historical Context
Timeline: Open Standards vs Proprietary Lock-in
- 1996: Adobe + Microsoft jointly create OpenType (OTF)
- 1997: Microsoft creates EOT separately for IE4 only
- 1996-2009: OTF gains universal adoption, EOT stays IE-exclusive
- 2009: WOFF created as open web font standard (based on OTF)
- 2012: WOFF becomes W3C standard, universal browser support
- 2018: WOFF2 becomes standard with better compression
- 2022: IE11 retired, EOT support drops to 0%
- 2025: OTF is universal standard, EOT is completely obsolete
Why OTF Succeeded: Open Collaboration
- • Joint development: Adobe + Microsoft worked together
- • Open specification: Published standard, anyone could implement
- • Universal adoption: All platforms and vendors supported it
- • Rich features: Advanced typography appealed to designers
- • Future-proof: Flexible enough to evolve with technology
Why EOT Failed: Proprietary Isolation
- • Single-vendor: Microsoft only, no industry collaboration
- • Proprietary: Closed format with DRM restrictions
- • Browser rejection: Chrome, Firefox, Safari refused to implement
- • DRM problems: URL binding broke legitimate use cases
- • No evolution: Frozen in time, couldn't adapt
Lesson: Open Standards Win
- • Collaboration beats isolation: OTF succeeded, EOT failed
- • Openness beats proprietary: Industry rejected lock-in
- • Cross-platform beats single-vendor: Universal > limited
- • Modern web fonts: WOFF/WOFF2 followed OTF's open model
Modern Recommendations
Always Use OTF (Desktop):
- • Desktop installation: OTF works on all platforms (Windows, macOS, Linux)
- • Design software: Full feature support in Adobe CC, Affinity, etc.
- • Typography: Complete access to ligatures, alternates, OpenType features
- • Professional printing: High-quality PostScript output
- • Font development: Industry-standard format for creation and editing
Convert OTF to WOFF2/WOFF (Web):
- • Web delivery: Convert OTF to WOFF2 (primary) + WOFF (fallback)
- • Browser support: WOFF2/WOFF covers 99%+ of users
- • Compression: WOFF2 provides 30% better compression than OTF
- • Modern standard: W3C recommended format
- • Tools: Use FontSquirrel, Transfonter, or fonttools for conversion
Never Use EOT:
- • Zero support: 0% browser coverage since IE11 retired (2022)
- • No desktop use: Cannot be installed on any OS
- • Completely obsolete: No modern application exists
- • Action: Delete all .eot files and remove EOT from CSS immediately
EOT Removal Checklist
- ☐ Find source OTF/TTF files (EOT was generated from these)
- ☐ Verify you have OTF/TTF versions
- ☐ Convert OTF/TTF to WOFF2 + WOFF for web
- ☐ Update CSS @font-face rules to use WOFF2/WOFF
- ☐ Remove all EOT format references from CSS
- ☐ Delete all .eot files from server/repository
- ☐ Test fonts in all target browsers
- ☐ Verify no IE-specific font fallbacks remain
- ☐ Document font sources and licenses
Modern Font Stack Example:
@font-face {
font-family: 'MyFont';
src: url('myfont.woff2') format('woff2'),
url('myfont.woff') format('woff');
font-weight: normal;
font-style: normal;
font-display: swap;
}
/* OLD (obsolete - REMOVE): */
/* src: url('myfont.eot'); */
/* src: url('myfont.eot?#iefix') format('embedded-opentype'); */Note: WOFF2 + WOFF covers 99%+ browsers. No need for EOT, TTF, or OTF in web CSS.
Summary: OTF vs EOT
OTF (OpenType Font) is the universal, cross-platform standard created by Adobe + Microsoft (1996) that works on all desktop operating systems, supports advanced typography, and serves as the source format for WOFF2/WOFF web fonts—achieving near-universal adoption through open collaboration. EOT (Embedded OpenType) was Microsoft's proprietary web font (1997) exclusive to Internet Explorer with DRM restrictions that other browsers rejected, and since IE11 retired (June 2022), EOT has 0% browser support and is completely obsolete. Use OTF for desktop installation on all platforms. Convert OTF to WOFF2/WOFF for web delivery (99%+ coverage). Delete all EOT files and remove EOT references from CSS immediately—EOT has zero use cases in 2025.
Written & Verified by
Sarah Mitchell
Product Designer, Font Specialist
OTF vs EOT FAQs
Common questions answered about this font format comparison