Do frame delays get reversed too, or just the frames?

Just the frame order. Each frame keeps its own original display duration; only the sequence they're shown in is flipped, so a fade-in with increasing delays becomes a fade-out with decreasing delays, not the other way around.

Is the loop count preserved?

Yes, the reversed animation keeps the exact same loop count (including infinite, if the original was set to loop forever) as the source file.

Does reversing lose any image quality?

No. Every frame is decoded to its exact original pixels and re-encoded the same way this category's APNG Creator does, so there's no additional lossy recompression beyond the file already being PNG (lossless).

What if my file isn't actually animated?

The tool requires a genuine APNG with an acTL chunk to decode; a plain PNG without one returns a clear error rather than a meaningless single-frame result.

APNG Reverser - Play an Animated PNG Backward

Overview

Introduction

This tool plays an existing animated PNG in reverse, without you needing to manually extract, reorder, and reassemble its frames.

It's built directly on this category's shared APNG decoder and encoder, so reversing is just a transform on already-decoded frame data.

What Is APNG Reverser?

An APNG frame-order reverser that fully decodes an uploaded animation's frames and delays, flips the order of the frame list, and re-encodes a new, valid APNG file from the flipped sequence.

The result is a complete, independent file — not a reference or a playback trick — that plays backward in any APNG-aware viewer.

How APNG Reverser Works

The uploaded file's bytes are decoded with this category's shared decoder into an ordered list of RGBA frames, each carrying its own delay.

That list is reversed in place (last frame first, first frame last), and the reversed list is handed straight to this category's shared encoder along with the original loop count to produce the output bytes.

When To Use APNG Reverser

Use it to create a backward-playing version of an animation — a common effect for reveal/undo transitions, rewind indicators, or playful loop variations.

It's also a fast way to check what an animation looks like in reverse without re-authoring it in an animation tool.

Often used alongside APNG Frames Extractor, APNG Creator and APNG Player.

Features

Advantages

Produces a genuine, independent APNG file rather than a CSS/JS playback trick, so it works anywhere a normal animated image is accepted.
Preserves each frame's original delay and the file's loop count exactly, only the play order changes.
Runs entirely client-side, reusing this category's already-tested decode/encode logic rather than any new, separate math.

Limitations

Inherits the same decode limitations as this category's frame extractor: no palette-indexed PNG support, and partial-frame dispose/blend operations aren't composited across frames.
Produces a new file rather than modifying the original in place, so both versions will exist unless you replace the source.

Examples

Reverse a fade-in animation

Input

A 10-frame fade-in APNG, frames 1-10 going transparent to opaque

Output

A new 10-frame APNG playing frames 10 down to 1, i.e. a fade-out

Flipping frame order turns any directional animation into its mirror-image in time.

Reverse a looping bounce

Input

A 6-frame bouncing-ball APNG, loop count 0

Output

A new 6-frame APNG with the same infinite loop count, playing the bounce backward

The loop count carries over unchanged; only the frame sequence is flipped.

Best Practices & Notes

Best Practices

Preview the reversed result with the APNG Player tool before relying on it, especially for animations with uneven per-frame delays.
If you only want to check the effect quickly, remember reversing is non-destructive — your original upload is never modified.

Developer Notes

The reversal logic itself is a single array reverse on the decoded frame list; the real work — decoding and re-encoding a spec-compliant APNG — is delegated entirely to this category's shared decodeApng/createApng functions rather than reimplemented, keeping this tool's own lib file intentionally thin.

APNG Reverser Use Cases

Creating a backward-playing variant of an existing animation for a rewind/undo effect
Turning a fade-in into a fade-out (or vice versa) without re-authoring the source animation
Quickly previewing how an animation reads when played in reverse

Common Mistakes

Expecting individual frame delays to reverse their values along with the order — only the sequence flips, each frame keeps its own original duration.
Uploading a non-animated PNG and expecting a meaningful result; reversal only makes sense for files with more than one frame.

Tips

Combine with the APNG Speed Changer tool to both reverse and retime an animation in two quick steps.
Use the APNG Frames Extractor first if you want to inspect the exact frame order before and after reversing.

APNG Reverser