Are my MP4 files uploaded anywhere?

No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.

Is converting MP4 to OPUS free?

Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.

Does converting MP4 to OPUS lose quality?

OPUS is a compressed format, so some data is discarded. At the default setting the difference is not visible; you can raise the quality setting if you need to be certain. Only the first soundtrack is kept. A film with a second language or a commentary track loses it.

Do I need to install anything to open OPUS files?

No installation is needed for the conversion itself — it runs in the browser you already have. Opening the OPUS afterwards needs whatever software normally handles Opus Audio on your device.

MP4toOPUS

Convert MP4 to OPUS

Up to 100 files at once. Mixed formats are fine.

You can convert MP4 to OPUS free and without an account: drop the file above and the OPUS is ready to download in a second or two. The conversion happens inside your own browser, so the file is never uploaded — it works on Windows, Mac, Linux, iPhone and Android, and keeps working with the network switched off.

What MP4 and OPUS are for

The video format that plays everywhere. If in doubt, this is the answer.

The best-sounding format at low bitrates. What voice messages and calls use.

How to convert MP4 to OPUS

Drop your MP4 file onto this page, or click to pick one.
Choose OPUS as the target. The conversion runs inside your browser — the file is never uploaded.
Download the finished OPUS file.

MP4 vs OPUS: what changes

MP4 compared with OPUS
	MP4	OPUS
Full name	MPEG-4 Video	Opus Audio
File extension	.mp4	.opus
Media type	video/mp4	audio/opus
Compression	Lossy — file size is bought with quality	Lossy — file size is bought with quality

Quality: Some quality is given up for a smaller file. At the default setting the difference is hard to see.
Where it runs: This conversion runs inside your browser. Your file is never uploaded, and it works with the network disconnected.
What can be lost: Only the first soundtrack is kept. A film with a second language or a commentary track loses it.

MP4 to OPUS: common questions

Are my MP4 files uploaded anywhere?: No. This conversion runs entirely inside your browser, so the file never leaves your device. You can confirm it yourself: open the network tab of your browser's developer tools and convert something. You will see the page load, plus the analytics and advertising the site is paid for with — and nothing carrying your file.
Is converting MP4 to OPUS free?: Yes. There is no account, no watermark and no limit on how many files you convert — it runs on your own machine, so it costs us nothing to let you. Files up to 100 MB are handled in the browser.
Does converting MP4 to OPUS lose quality?: OPUS is a compressed format, so some data is discarded. At the default setting the difference is not visible; you can raise the quality setting if you need to be certain. Only the first soundtrack is kept. A film with a second language or a commentary track loses it.
Do I need to install anything to open OPUS files?: No installation is needed for the conversion itself — it runs in the browser you already have. Opening the OPUS afterwards needs whatever software normally handles Opus Audio on your device.