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Animated Portable Network Graphics

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name APNG (Animated Portable Network Graphics)
Description

APNG or Animated Portable Network Graphics is an extension of the PNG, Portable Network Graphics raster image format but extends beyond static images to support frame-based animated images. Documented together in the same W3C specification, APNG shares much of the same structure but adds three additional chunk types describing the animation and providing additional frame data:

  • acTL: Animation Control Chunk which declares that this is an animated PNG image, gives the number of frames, and the number of times to loop. acTL must must appear before the first IDAT chunk within a valid PNG stream.
  • fcTL: Frame Control Chunk defines the dimensions, position, delay and disposal of an individual frame. Exactly one fcTL chunk chunk is required for each frame.
  • fdAT: Frame Data Chunk contains the image data for all frames (or, for animations which include the static image as first frame, for all frames after the first one). At least one fdAT chunk is required for each frame, except for the first frame, if that frame is represented by an IDAT chunk.

See PNG, Portable Network Graphics for general description as well as other chunk definitions.

The specification notes that APNG is backwards-compatible with earlier versions of PNG; a non-animated PNG decoder will ignore the ancillary APNG-specific chunks and display the static image.
Production phase May be an initial-state or middle-state format; more often used as final-state format.
Relationship to other formats
    Extension of PNG, Portable Network Graphics

Local use Explanation of format description terms

LC experience or existing holdings See PNG, Portable Network Graphics.
LC preference See PNG, Portable Network Graphics.

Sustainability factors Explanation of format description terms

Disclosure See PNG, Portable Network Graphics.
    Documentation See PNG, Portable Network Graphics.
Adoption

See also PNG, Portable Network Graphics.

In 2025, CanIUse reports strong support of APNG across many major browsers with the notable exception of IE.

The 2016 article iMessage stickers and the “misterious” APNG file. Everything we learned so far mentions that APNG is an accepted formats for animated stickers in iOS10 iMessage apps with many other applications following suit including Signal added support in 2021 as well as Discord.

    Licensing and patents See PNG, Portable Network Graphics.
Transparency See PNG, Portable Network Graphics.
Self-documentation

See PNG, Portable Network Graphics.

Accessibility Features

See PNG, Portable Network Graphics.
External dependencies See PNG, Portable Network Graphics.
Technical protection considerations See PNG, Portable Network Graphics.

Quality and functionality factors Explanation of format description terms

Still Image
Normal rendering See PNG, Portable Network Graphics.
Clarity (high image resolution) See PNG, Portable Network Graphics.
Color maintenance See PNG, Portable Network Graphics.
Support for vector graphics, including graphic effects and typography See PNG, Portable Network Graphics.
Functionality beyond normal rendering APNG supports animation.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension apng
 The PNG standard recommends the use of apng as extension.
Internet Media Type image/apng
 See registration at IANA.
Internet Media Type image/vnd.mozilla.apng
 Deprecated media type listed in registration at IANA.
Magic numbers Hex: 89 50 4e 47 0d 0a 1a 0a
ASCII: \211 P N G \r \n \032 \n
 Documented in PNG standard. Same as PNG, Portable Network Graphics.
Other See related format.  See PNG, Portable Network Graphics.
Pronom PUID fmt/935
 See https://www.nationalarchives.gov.uk/PRONOM/fmt/935 for Animated Portable Network Graphics.
Wikidata Title ID Q433224
 See https://www.wikidata.org/wiki/Q433224.

Notes Explanation of format description terms

General  
History

APNG was added to the PNG specification in 2022. See PNG, Portable Network Graphics for overall format history.

Format specifications Explanation of format description terms


Useful references

URLs


Last Updated: 07/17/2025

 
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