What is EOT?

EOT was Microsoft's web font format - compressed OpenType/TrueType fonts with root string DRM (domain restriction). Created to enable @font-face CSS embedding while protecting font licensing. Only supported by Internet Explorer (IE6-IE11) and legacy Edge (pre-Chromium). MicroType Express compression reduces file size. Root strings limit font usage to specific domains, preventing unauthorized distribution. Includes subsetting (character reduction) for smaller downloads.

EOT dominated web fonts from 2008-2012 when IE was the dominant browser and cross-browser web fonts were rare. Developers created CSS fallback stacks: EOT for IE, TTF/OTF for others. W3C rejected EOT as standard, instead standardizing WOFF (Web Open Font Format) in 2010. Modern browsers (Chrome, Firefox, Safari) never supported EOT. Microsoft Edge (Chromium, 2020+) dropped EOT support. Today, EOT is obsolete - WOFF2 offers superior compression and universal support. Still found in legacy websites targeting old IE versions.

Note: EOT is obsolete - use WOFF2 for modern web fonts with universal browser support!

History

Microsoft developed EOT to enable web fonts in Internet Explorer with licensing protection, but it never achieved cross-browser adoption and was superseded by WOFF.

Key Milestones

  • 1997: EOT introduced (IE4)
  • 2008: @font-face revival (IE6+)
  • 2010: WOFF standardized (W3C)
  • 2012: WOFF adoption grows
  • 2020: Edge drops EOT support
  • Present: Obsolete, legacy only

Key Features

Core Capabilities

  • Compression: MicroType Express
  • DRM: Root string domain restriction
  • Subsetting: Character reduction
  • IE Support: Internet Explorer only
  • Legacy: Obsolete format
  • @font-face: CSS embedding

Common Use Cases

Legacy Websites

Old IE compatibility

Historical

Web font archives

Obsolete

No modern use cases

Deprecated

Replace with WOFF2

Advantages

  • Compression (smaller than TTF/OTF)
  • DRM/domain restriction
  • Worked in old Internet Explorer
  • Subsetting for file size reduction
  • Historical importance (pioneered web fonts)

Disadvantages

  • Obsolete (no modern browser support)
  • IE-only (never cross-browser)
  • Proprietary Microsoft format
  • Inferior to WOFF2 compression
  • Dropped by Microsoft Edge (2020)
  • No reason to use today

Technical Information

Format Specifications

Specification Details
File Extension .eot
MIME Type application/vnd.ms-fontobject
Compression MicroType Express
Base Format OpenType/TrueType
Browser Support IE6-IE11, legacy Edge (obsolete)
Status Obsolete, deprecated

Common Tools

  • Creation: ttf2eot, Font Squirrel generator (historical)
  • Modern Alternative: WOFF2 (use instead)
  • Conversion: Online converters (TTF/OTF → WOFF2)
  • Recommendation: Do NOT use EOT for new projects