Online Video Converter

mp4 · webm · mov

Extract MP3 audio from a video, shrink its file size, or convert it to MP4 or WEBM. Your browser processes one file at a time, so it never leaves your device.

Settings
QueueNothing is uploaded

Drop a video file here

Supports MP4, WEBM, MOV, AVI and MKV

Processing video…

About this video converter

The tool has three action modes. Extract MP3 audio from video pulls out the audio track and encodes it as an MP3, the same way the audio converter does. Compress video file size and Convert video to MP4 / WEBM both re-encode the video itself: when your browser supports WebCodecs and the file is MP4, MOV or M4V, the video is decoded and re-encoded with your browser's own H.264 encoder, then muxed into a new MP4 with mp4box.js and mp4-muxer. For other containers, such as WEBM, MKV or AVI, or when WebCodecs is not available, the tool instead plays the file and records the result with MediaRecorder.

Convert video to MP4 / WEBM keeps the original frame size, up to a 4096 px long edge, and caps the video bitrate at 85% of the source. It is a re-encode, not an exact copy of the source. Compress video file size scales the frame down to a 720 px long edge and aims for roughly half the source bitrate. Neither preset can be adjusted.

How to use it

01

Add a video file

Drop it on the box, or click it to choose one. Only one file at a time, up to 100 MB.

02

Pick an action mode

Choose Extract MP3 audio from video, Compress video file size, or Convert video to MP4 / WEBM.

03

Process it

Click Process video. When the result is ready, it appears with a Download button.

What it does

  • Your browser does the work; the video is never uploaded, though the mp4box.js, mp4-muxer and LAME libraries are downloaded from their CDNs the first time you need them.
  • Extract MP3 audio from video always produces a 192 kbps MP3, encoded with the same LAME encoder as the audio converter.
  • Convert keeps the original frame size and caps the bitrate at 85% of the source. Compress scales to a 720 px long edge and targets roughly half the source bitrate.
  • When your browser supports WebCodecs and the file is MP4, MOV or M4V, encoding runs off the real-time clock and can finish well before the clip's own length. Otherwise the tool plays the video in real time to record the result.
  • The result waits behind a Download button, so nothing is saved until you click. Files are handled one at a time, and there is no ZIP.

Specifications

Specification Details
Accepts One video file at a time: MP4, WEBM, MOV, AVI or MKV, up to 100 MB
Action modes Extract MP3 audio, compress video file size, or convert video to MP4 or WEBM
Audio extraction 192 kbps MP3, via the LAME encoder (lamejs 1.2.1) in a Web Worker, loaded from the cdnjs CDN
Fast video path WebCodecs H.264 encoding for MP4, MOV and M4V files, muxed with mp4box.js 0.5.2 and mp4-muxer 5.2.1 from the jsDelivr CDN
Convert preset Keeps the source frame size, capped at 4096 px on the long edge; bitrate capped at 85% of the source video's bitrate
Compress preset Scales to a 720 px long edge; targets roughly 55% of the source video's bitrate
Fallback path Plays the file in real time and records it with MediaRecorder at 30 fps, preferring H.264 in MP4 and falling back to WEBM
Where your file goes Nowhere. It stays in this tab's memory
Good to know

What the converter does not do

It works with one fixed preset per mode and no manual settings. Some jobs need a different tool.

Audio can go missing

The fast WebCodecs path only copies the audio track when it is already AAC. If the source audio uses another codec, such as PCM in some MOV screen recordings, the result has no audio and no error is shown.

No quality, resolution or bitrate choice

Compress and convert each run one fixed preset. There is no slider or setting to change what they target.

Convert still re-encodes

Convert video to MP4 / WEBM is not a lossless remux. It caps the bitrate at 85% of the source, so file size and quality can still change.

MP4 or WEBM is not your choice

The output container depends on what your browser's pipeline can produce, not on a setting you control.

One file at a time, up to 100 MB

There is no batch mode and no way to raise the size cap.

The fallback runs at real speed

When WebCodecs is unavailable or the file is not MP4, MOV or M4V, the tool plays the video to record it, so a 10 minute clip takes about 10 minutes, and it depends on your browser being able to play the file at all.

Related tools

MOV to MP4 QuickTime recordings into a format everything plays. Video compressor Re-encode a video at a lower bitrate to shrink the file. MP4 to MP3 Extract the audio track as a 192 kbps MP3. Audio converter Batch convert between the four common audio formats.
All audio and video tools → How video compression actually works →

Frequently asked questions

No. Your browser processes the file in this tab. The mp4box.js, mp4-muxer and, for audio extraction, LAME libraries are downloaded from their CDNs the first time you need them, but the video and audio themselves are never sent anywhere.

The fast WebCodecs path only copies the audio track when it is already AAC. If the source audio uses a different codec, the result has no audio and no error is shown. This is a limitation of that path; there is no setting to change it.

No. Compress and convert each use one fixed preset. Compress scales to a 720 px long edge at roughly half the source bitrate; convert keeps the original frame size and caps the bitrate at 85% of the source.

No. It re-encodes the video and caps its bitrate at 85% of the source, so file size and quality can still change even though the mode is meant for format conversion rather than compression.

Whichever your browser's pipeline produces: MP4 with H.264 when the browser supports encoding it, WEBM otherwise. There is no format picker despite the option's name.

That happens on the fallback path, used when WebCodecs is not available or the file is not MP4, MOV or M4V. It plays the video in real time to record the result, so a 10 minute clip takes about 10 minutes.

Your file stays on your device

Your browser decodes and re-encodes the file inside this tab. It is not uploaded or stored anywhere. The mp4box.js, mp4-muxer and LAME libraries load from their CDNs the first time you need them.