Is it free to convert between AU and OPUS?

Yes, Convert999 is 100% free. All conversions happen locally in your browser with no file size limits, no registration, and no watermarks.

.au

.opus

AU vs OPUS

Compare Sun Audio and Opus Audio formats — understand the key differences and when to use each

Format Overview

AU

Sun Audio

Sun Audio (.au) is a audio file format.

.auaudio

OPUS

Opus Audio

Opus Audio (.opus) is a audio file format.

.opusaudio

AU vs OPUS: Feature Comparison

Feature	AU	OPUS
Full Name	Sun Audio	Opus Audio
File Extension	.au	.opus
Category	audio	audio
Free to Convert	✓ Yes	✓ Yes
Browser Support	✓ All Browsers	✓ All Browsers
Convert to Each Other	✓ Yes	✓ Yes

When to Use AU vs OPUS

Use AU when you need:

•Files in Sun Audio format for maximum compatibility
•Industry-standard audio format support
•Wide software and platform compatibility

Use OPUS when you need:

•Files in Opus Audio format for specific workflows
•Optimized audio format features
•Modern format advantages and smaller file sizes

Convert Between Them

AU OPUS OPUS AU

ファイルを選択

またはファイルをここにドラッグ＆ドロップ

最大ファイルサイズ：2GB

ファイルはブラウザ内でローカルに処理されます。サーバーにアップロードされません。

Learn More About These Formats

AU Converter OPUS Converter

Frequently Asked Questions

What is the difference between AU and OPUS?

AU (Sun Audio) and OPUS (Opus Audio) are both audio file formats. AU files use the .au extension while OPUS uses .opus. They differ in compression, quality, compatibility, and intended use cases.

Can I convert AU to OPUS for free?

Yes! Convert999 lets you convert AU to OPUS completely free, directly in your browser. No file upload to any server, no registration needed — your files stay private on your device.

Which is better, AU or OPUS?

It depends on your use case. AU (Sun Audio) may be better for certain workflows, while OPUS (Opus Audio) excels in others. Consider factors like file size, quality, software compatibility, and your specific needs.

Is it safe to convert files on Convert999?

Absolutely. Convert999 processes all files 100% locally in your browser. Your files are never uploaded to any server, ensuring complete privacy and security.

AU Converter

Convert from AU

OPUS Converter

Convert from OPUS

File Tools

Compress, resize, merge

Convert to AU

All sources → AU

Convert to OPUS

All sources → OPUS

Format Statistics

Trends & data 2025

More Format Comparisons

JPGvsPNG PNGvsWEBP JPGvsWEBP SVGvsPNG HEICvsJPG BMPvsJPG TIFFvsJPG GIFvsPNG

Feature