Convert APNG to WEBM Online

APNG vs WebM — Which Should You Convert To?

If your animated PNG has grown to several megabytes, you are weighing an image against a video. The short answer: keep APNG when the transparent background is the point and the loop is short; convert to WebM when the clip is long, heavy, or headed for a page where it can live in a <video> element. WebM re-encodes the animation with a VP-family codec and typically collapses the file size — at the cost of the alpha channel, which is composited onto a solid Background Color during the encode.

Side-by-side Comparison

When to Keep APNG

• The animation sits on a coloured, textured, or unpredictable background and the alpha channel has to survive.
• It has to work anywhere an image works — an <img> tag, a CSS background, an avatar upload field, a chat client that accepts PNG.
• The loop is short and small enough that the download cost is not worth a second format.
• You want a lossless master to re-export from later; APNG never re-compresses your frames.

When to Convert to WebM

• The APNG is heavy — long loops, high frame counts, or photographic content, all of which lossless DEFLATE handles badly.
• The animation is going into a page where you control the markup and can use a muted, looping <video> element.
• You want hardware-accelerated decoding: video decode is cheaper on battery and CPU than repainting hundreds of full PNG frames.
• The background is a known solid colour, so flattening the transparency onto it costs you nothing visually.

Which WebM Codec to Choose

How to Convert APNG to WebM

1. Upload Your APNG File: Drag and drop your .apng onto the page or click "Add Files"; animated .png files work too, and each upload becomes its own WebM.
2. Set the Quality Preset: Under File Compression, Quality Preset starts at Very High (Recommended), which targets a visually lossless encode — about CRF 20 when the codec is VP9 or AV1; drop to High or Medium for a smaller file, or switch to Constant Quality to type a CRF value yourself.
3. Pick the Background Color and Video resolution: Background Color (White by default) replaces the transparency your APNG carries; the same colour fills any letterbox bars. Video resolution stays on Keep original unless you pin it to a preset, a percentage, or an exact Width × Height. The Video Codec control in the advanced options switches between VP9, VP8, and AV1.
4. Convert and Download: Click Convert and save the .webm. Uploads travel over an encrypted connection, run on our servers, and are deleted automatically after a few hours — no sign-up, no watermark.

Frequently Asked Questions

Can the WebM keep my APNG's transparent background?

Not from this converter. The encode produces ordinary opaque video, and every transparent pixel is composited onto the Background Color — white unless you change it — before the frames are compressed. If the alpha channel is the reason the animation exists, stay in an image format: APNG to GIF keeps every frame plus a single transparent index, and APNG to WebP keeps a full 8-bit alpha channel on the first frame as a still image.

Will converting to WebM lose quality compared with the APNG?

Some, by design. APNG is lossless — every pixel of every frame is stored exactly — while VP8, VP9, and AV1 are lossy codecs that discard detail your eye is unlikely to catch. At the Very High preset the difference is hard to see at normal playback speed, and it buys an enormous size reduction. If you need a pixel-exact archive, keep the original APNG as your master and treat the WebM as a delivery copy.

Does the WebM keep every frame and the original timing?

Yes. An animated PNG is detected as a frame sequence and decoded like a video source, so all frames are re-encoded with the delays stored in the file. You do not get a per-image duration control on this page because the animation already carries its own timing.

Why is the WebM silent?

Because the source is. An APNG has no audio track, so the converter writes a video-only WebM. That turns out to be convenient on the web: browsers only autoplay video that is muted, so a silent file plays inline without a user gesture as long as you add muted, loop, autoplay, and playsinline to the <video> tag.

Is WebM or MP4 the better replacement for an animated PNG?

WebM if you control the page: it is royalty-free, its VP9 encoder tends to beat H.264 on flat animated content, and support now sits near 96% of users. MP4 if the file has to travel — messaging apps, social uploads, editors, and older Safari installs all handle H.264 in MP4 more predictably. APNG to MP4 is one click away, and serving both from a single <video> element with two <source> tags is a common belt-and-braces approach.

How much smaller will the WebM be than the APNG?

Usually dramatically smaller, because you are swapping lossless per-frame storage for motion-compensated video: WebM only encodes what changed between frames, which is exactly what an APNG cannot do. The savings are biggest on long loops and on animation with large static areas, and smallest on very short clips where container overhead dominates. Content with heavy per-frame noise compresses least well in both formats.

Which browsers can play the WebM I get back?

Chrome from version 25, Firefox from 28, Edge from 79, and Safari from 16 handle WebM natively — roughly 96% of global browser usage, with Safari 12.1 to 15.6 offering only partial support. That is effectively the same reach as APNG itself, so the choice between them is about transparency and file size rather than compatibility.

What happens to my uploaded APNG file after the conversion?

It is uploaded over an encrypted (TLS) connection, converted on our servers, and deleted automatically after a few hours. There is no sign-up, no watermark, and files are never shared or made public. If you later want to go the other way, WebM to GIF turns a clip back into a looping image.