How do I convert a file online for free?

Drop your file onto FileFettle, select your output format, and click Convert. Your file is processed instantly inside your browser — no upload, no registration, completely free.

Do I need to upload my files to convert them?

No. FileFettle runs entirely in your browser using WebAssembly and the Canvas API. Your files never leave your device and are never sent to any server.

What file formats can I convert?

FileFettle supports over 80 formats: Images (JPG, PNG, WebP, AVIF, HEIC, GIF, SVG, TIFF, BMP), Audio (MP3, WAV, FLAC, OGG, AAC, M4A, OPUS, AIFF, WMA), Video (MP4, WebM, MOV, AVI, MKV, WMV, MPEG), Documents (PDF, DOCX, TXT, HTML, Markdown), and Data (CSV, JSON, XML, YAML, XLSX, XLS, ODS, TOML, INI).

Is there a file size limit?

No. Since conversion runs locally in your browser, there is no server-side file size limit. The only constraint is your device's available memory.

Is FileFettle free to use?

Yes — completely free, forever. No subscriptions, no paywalls, no ads, no tracking.

Can I convert video files in my browser?

Yes. FileFettle uses FFmpeg compiled to WebAssembly to convert audio and video files directly in your browser, with no server upload required.

How do I convert an image to WebP, PNG or JPG?

Drop your image file onto FileFettle (supports JPG, PNG, HEIC, GIF, TIFF, BMP, SVG, AVIF and more), choose WebP, PNG, or JPG as the output format, optionally resize or adjust quality, then click Convert to download instantly.

Convert AAC to OPUS Online

State-of-the-art codec. Excellent at low bitrates. Runs entirely in your browser — no upload, no registration, completely free.

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Drop your AAC files here

or click to browse — multiple files supported

🔒 Files never leave your device

Why convert AAC to OPUS with FileFettle?

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100% Private

Your files are processed locally in your browser. Nothing is ever uploaded to any server.

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No file size limit

Convert files of any size — the only limit is your device's available memory.

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Completely free

No subscriptions, no paywalls, no account required. Free forever.

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Any browser

Chrome, Firefox, Safari, Edge — no plugins or software to install.

How to convert AAC to OPUS

1
Drop your AAC file onto the converter above, or click to browse and select it from your device.
2
FileFettle processes the file instantly using FFmpeg compiled to WebAssembly. No uploading required.
3
Click the Download button to save your converted OPUS file directly to your device.

Need a different format? FileFettle supports 80+ audio conversions.

Explore all formats →