What is APNG and where did it come from?
APNG, short for Animated PNG, is an extension of the PNG format that adds animation. It was created by Mozilla around 2004 as a way to bring frame-based animation to the web without giving up PNG's strengths. It isn't part of the original PNG specification — it's a separate extension layered on top of it — but it stores its animation inside a standard PNG file.
How does APNG stay backwards-compatible?
This is APNG's clever trick. The file begins with a normal PNG image that acts as the first frame, and the extra animation frames are tucked into chunks that older software is free to ignore. So a viewer that doesn't support APNG simply shows that first frame as an ordinary still PNG, while an APNG-aware viewer plays the full animation. Nothing breaks — you just lose the motion.
How does APNG compare with GIF?
Because APNG inherits PNG's capabilities, it carries full 24-bit truecolour and a complete alpha channel for smooth, semi-transparent edges. GIF is limited to 256 colours per frame and only hard on/off transparency, which produces banding and jagged edges. The upshot is that APNG animations look noticeably better, especially for gradients, photos, and anything that needs to blend cleanly over a background.
Do browsers and apps support APNG?
All modern browsers support APNG, including Firefox, Chrome, Edge, and Safari, so it plays reliably on the web. The catch is that because it isn't part of the original PNG spec, some older or simpler image software ignores the animation and only ever shows the first frame. Files usually keep the .png extension, though you'll sometimes see .apng.
When should you use APNG?
Reach for APNG when you want a short animation with high colour fidelity or soft transparency — UI flourishes, stickers, and logos that need to sit cleanly on any background. If you just need a single still image, plain PNG is enough. And if you're weighing APNG against the older animated standard, the PNG vs GIF comparison covers the trade-offs in detail.
Frequently asked questions
- What file extension does APNG use?
- APNG files usually use the normal .png extension, though some tools use .apng. Either way, the animation lives inside a file that any PNG viewer can open.
- Will an APNG break in apps that don't support it?
- No. APNG is backwards-compatible, so software that doesn't understand the animation simply displays the first frame as an ordinary still PNG.
- Is APNG better than GIF?
- For quality, yes. APNG keeps PNG's 24-bit truecolour and full alpha transparency, so it avoids GIF's 256-colour limit and hard-edged transparency.
- Can a normal PNG be animated?
- No. Standard PNG holds a single still image. Animation requires the APNG extension, which adds the extra frames on top of the base PNG.