What is a .apng file?
Animated Portable Network Graphics · Image · Mozilla Foundation · 2008
APNG extends the ordinary PNG format with looping animation, keeping PNG's full colour depth and real alpha transparency instead of GIF's 256-colour palette. Every major browser now supports it, and in 2025 it was folded directly into the official PNG specification.
What is a .apng file used for?
APNG adds an 'acTL' (animation control) chunk plus per-frame 'fcTL' and 'fdAT' chunks to an ordinary PNG, giving it multiple timed frames without changing the base PNG structure.
That design keeps it backward compatible: a viewer that does not understand animation simply shows the first, default frame, because the PNG specification says unknown ancillary chunks should be ignored.
Unlike GIF, an APNG frame can use full 24-bit colour plus an 8-bit alpha channel, so gradients and semi-transparent edges stay smooth instead of banding or getting a hard cutout edge.
Firefox and Safari supported it for years before Chrome added it in 2017; all major browsers now render APNG natively, and in June 2025 it became part of the official PNG specification itself as a W3C Recommendation.
How to open a .apng file
The .apng format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- Any modern browser
- GIMP
- IrfanView (recent versions)
macOS
- Any modern browser
- GIMP
Linux
- Any modern browser
- GIMP
Web
- Every modern browser
How to convert a .apng file
You can convert a .apng file to GIF, WebP, PNG using a conversion tool or the export menu of an app that opens it.
Convert images free: ImageConvert
.apng file signature (magic bytes)
Programs recognise a .apng file by the bytes at the start of the file, not by its name. These are the signatures for APNG. For a full breakdown, see the APNG file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 89 50 4E 47 0D 0A 1A 0A | 0 | PNG signature; an 'acTL' chunk before the image data marks the file as animated |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .apng file?
APNG extends the ordinary PNG format with looping animation, keeping PNG's full colour depth and real alpha transparency instead of GIF's 256-colour palette. Every major browser now supports it, and in 2025 it was folded directly into the official PNG specification.
Is APNG the same as a GIF?
They do the same basic job, a short looping animation, but APNG keeps full colour and real per-pixel transparency, where GIF is limited to 256 colours per frame and one fully transparent colour.
Why does my APNG only show one frame?
An older browser or image viewer may not support APNG animation and is falling back to the default frame, which every APNG includes for exactly this case. Support is now broad, so updating the app usually fixes it.
Related formats
Sources
Details on this page were checked against authoritative references: