APNG Checker
Check if a PNG is an animated PNG (APNG). See frame count, loop count, and dimensions. Runs entirely in your browser.
Drop a PNG here, paste it, or click to browse
You can check several files at once.
Files are read in your browser and never uploaded.
Check if a PNG is animated
Not sure whether a .png file is actually an animation? Drop it above and this checker reads the file's bytes to tell you instantly whether it's an animated PNG (APNG) or a plain static PNG — along with the frame count, how many times it loops, and its dimensions. Everything runs in your browser, so your image never leaves your device.
What is an APNG?
APNG (Animated Portable Network Graphics) extends the regular PNG format to store an animation — a sequence of frames with per-frame timing — while remaining backward-compatible. Open an APNG in a viewer that doesn't support animation and you simply see the first frame, a normal PNG. Unlike GIF, APNG keeps full 24-bit color and proper alpha transparency, which is why it's popular for stickers, emotes, and crisp UI animations.
How APNG detection works (the acTL chunk)
A PNG file is a signature followed by a series of chunks (length, 4-letter type, data, CRC). A file is an APNG when it contains an acTL (animation control) chunk before the first IDAT (image data) chunk. The acTL chunk stores the number of frames and the loop count (0 means it loops forever). This tool walks the chunks, finds acTL, and reports those values. If acTL appears after the first IDAT, most decoders treat the file as a static PNG — and the checker flags that too.
APNG vs GIF vs WebP
| Format | Colors | Transparency | Notes |
|---|---|---|---|
| APNG | 24-bit (millions) | Full alpha | Great quality, widely supported, larger files |
| GIF | 256 max | 1-bit (on/off) | Universal legacy support, lowest quality |
| Animated WebP | 24-bit | Full alpha | Usually smallest files, modern support |
Frequently Asked Questions
- What is an APNG?
- APNG (Animated Portable Network Graphics) is an extension of the PNG format that stores an animation — multiple frames with timing — while staying backward-compatible with PNG. Viewers that do not support APNG simply show the first frame as a normal static image.
- How do I know if a PNG is animated?
- A PNG is animated (an APNG) if it contains an "acTL" (animation control) chunk before the first image-data (IDAT) chunk. This tool reads the file's bytes, finds that chunk, and reports the frame count and loop count.
- Does this tool upload my file?
- No. The file is read locally with the browser's FileReader and parsed in JavaScript. Nothing is sent to a server, so it works offline and keeps your images private.
- Why does my APNG show as a static image?
- Two common reasons: the viewer/app does not support APNG (it then shows only the first frame), or the acTL chunk appears after the first IDAT, which makes most decoders treat the file as a static PNG. This checker flags that second case.
- APNG vs GIF vs WebP — what should I use?
- APNG supports 24-bit color and full alpha transparency (far better than GIF's 256 colors and 1-bit transparency) and is widely supported in modern browsers. Animated WebP usually produces smaller files but has slightly different tooling. GIF has the broadest legacy support but the lowest quality.