File Converter

WebM to Opus converter Free, private, no upload.

Convert WebM files to Opus right in your browser. Opus gives the best quality per kilobyte of any common audio format, especially for speech. Your files are never uploaded.

or drop files anywhere · paste with Ctrl/⌘ + V

How to convert WebM to Opus

  1. 1 Drop your WebM files onto the page, or click “Choose files”. You can add many at once, or a whole folder.
  2. 2 Opus is already selected as the output. Optionally open Options to adjust bitrate, sample rate, channels.
  3. 3 Click Convert, then Save. Converting several files? Save them all as one ZIP.

About the formats

WebM · WebM video

WebM is an open video format made for the web, using VP8/VP9 video and Opus or Vorbis audio.

Opus · Opus audio

Opus is a modern open audio codec with excellent quality at low bitrates. WhatsApp voice messages and many VoIP apps use it.

The conversion runs on your device using FFmpeg compiled to WebAssembly. You can adjust: bitrate, sample rate, channels, normalise loudness, start at, end at.

Frequently asked questions

How do I convert WebM to Opus?

Drop your WebM files onto the page, or click “Choose files”. You can add many at once, or a whole folder. Opus is already selected as the output. Optionally open Options to adjust bitrate, sample rate, channels. Click Convert, then Save. Converting several files? Save them all as one ZIP.

Are my files uploaded to a server?

No. The conversion runs entirely in your browser using WebAssembly. Your files never leave your device, so it is safe for private photos, contracts and business data. Once the page has loaded it even works offline.

Will converting WebM to Opus reduce quality?

Opus uses lossy compression, so some detail is traded for a smaller file. At the default quality the difference is very hard to see or hear, and you can raise the quality setting if you need more.

Can I convert multiple WebM files to Opus at once?

Yes. Add as many WebM files as you like; they are converted in parallel on your device and you can download them all as a single ZIP.

Is it free? Are there limits?

It is free, with no sign-up, no watermark and no daily limits. Because nothing is uploaded there is no upload size limit either; the only limit is your device’s memory, which matters mostly for very large videos.

See everything the WebM converter and the Opus converter can do.