EPUB 3.3

What the specification defines

EPUB 3.3 scores

Deterministic scores calculated from the structured facts above. Identical facts always produce identical scores.

• Archiving score

  100
  • it is a current, actively maintained format
  • an official specification document is publicly reachable
  • it is actively maintained and current

  Confidence 37% · evidence coverage 78%

• AI score

  100
  • an official specification document is publicly reachable

  Confidence 41% · evidence coverage 29%

• Openness score

  100
  • an official specification document is publicly reachable

  Confidence 41% · evidence coverage 60%

• Longevity score

  92
  • it is actively maintained and current
  • an official specification document is publicly reachable
  • it is a current, actively maintained format
  • it occupies a niche corner of the ecosystem

  Confidence 38% · evidence coverage 100%

Related to EPUB 3.3

Data quality

Every claim on this page is classified as a verified fact, a derived fact or an assumption.

Overall confidence

90%

Verification status

verified

Last reviewed

2026-08-03

Verified facts

2

2 classified claims backed by 2 sources.

• Convert Always editorial review — Convert Always
• EPUB 3.3 — W3C

Sources and review status