AU to PNG Converter
Processing entirely on your device — large files may take a moment.
Convert to PNG when you need lossless quality or a transparent background — for logos, UI screenshots and line art. If your files are still in AU format, this page is the shortcut: AU is the µ-law audio format of old Unix systems and Java applets — tiny mono files from another era.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How AU compares to PNG
| AU | PNG | |
|---|---|---|
| Compression | µ-law or PCM | Lossless (DEFLATE) |
| Best for | Old system sounds and recordings | Screenshots, logos, sharp graphics |
How to convert AU to PNG
- 1
Select your files
Select your AU audio file.
- 2
Convert instantly
The engine decodes the audio and draws its amplitude envelope as a clean waveform image.
- 3
Download results
Download the PNG — perfect for episode art, docs and presentations.
About the AU format
AU is Sun Microsystems' audio format from the Unix workstation age: a small header followed by µ-law (or PCM) samples. Java's applet era shipped it everywhere, and old Unix sound tooling still emits it.
Modern players increasingly skip it. Converting AU to WAV preserves the samples bit-for-bit while moving the file into universal territory — the standard rescue path for system sounds and old recordings.
+ Strengths
- ✓Simple, lossless sample storage
- ✓Native to old Unix/Java tooling
! Limitations
- −µ-law flavor sounds dated and mono
- −Dropped by modern players
About the PNG format
PNG was created in 1996 as a free, open replacement for the patent-encumbered GIF, and it has been the reference lossless image format ever since. Pixels are compressed with the DEFLATE algorithm (the same one inside ZIP files), which reproduces the original image exactly — bit-for-bit — while supporting full 8-bit or 16-bit alpha transparency. Screenshots, logos, icons, charts and anything with text or sharp edges should live in PNG.
Because it never discards information, PNG files of photographs are several times larger than JPG — that is the price of perfection. Modern PNG encoders add filters per scanline that make screenshots and flat-color graphics compress surprisingly well. PNG also became the base of APNG, the animation extension that browsers play natively.
+ Strengths
- ✓Truly lossless — every pixel survives exactly as it was
- ✓Full alpha transparency with smooth edges, not 1-bit masks
- ✓Open standard, unpatented, with excellent tooling everywhere
- ✓Ideal for text, line art and flat-color graphics — sharp edges stay sharp
! Limitations
- −Photographs become several times larger than JPG
- −Base format has no animation (that is the APNG extension)
- −16-bit or high-resolution PNGs can grow very heavy
Why convert AU to PNG?
There is a concrete reason this conversion exists: µ-law flavor sounds dated and mono PNG sidesteps that — Truly lossless — every pixel survives exactly as it was If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this AU to PNG converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Will I lose quality converting AU to PNG?
No — PNG is a lossless format, so every pixel of the converted image matches your original AU file. You can also adjust the quality/size balance before converting when the target format supports compression.
Can I convert a whole folder of AU files?
You can select many files at once and they are processed in a single batch. Output files land in one ZIP download when there is more than one result.
Will converting AU to PNG reduce audio quality?
If PNG is lossless, the output contains everything the AU file contains — no further loss is added. If PNG is lossy, one recompression pass is unavoidable; the quality slider controls how much. Loss that already happened in the source file can never be undone by converting.