Subformer
Free · No signup · Runs in your browser

Free Online File Converter for Video & Audio

Convert MP4, MOV, MKV, WebM, MP3, WAV, OGG, and more directly in your browser. Hardware-accelerated via WebCodecs — fast, private, and nothing is uploaded.

How to convert a file online

  1. 01

    Drop a video or audio file

    Drag a file onto the converter, or click to pick one — works with MP4, MOV, MKV, WebM, MP3, WAV, and most common formats.

  2. 02

    Choose the output format

    Pick a one-click preset (e.g. MP4 → MP3) or select any format from the dropdown.

  3. 03

    Convert and download

    Click Convert. The browser handles the rest — watch the progress bar, then download your new file.

Everything you need to convert media

Private by design

Your file never leaves your device. Reading, decoding, encoding, and writing all happen in your browser — we can't even see the filename.

Hardware-accelerated

Powered by WebCodecs, the same video engine your browser uses for YouTube and Netflix. MOV ↔ MP4 conversions are often fast remuxes with no re-encode.

Video ↔ audio extraction

Upload a video, pick an audio format, and get just the audio. Great for turning talks, lectures, and podcasts into MP3s.

MP4 fast-start

MP4 output is produced with its moov atom at the start of the file — ideal for streaming and direct web playback.

Zero install

No desktop app, no plugin, no command-line ffmpeg. Open the page, drop a file, get a result.

Cancel anytime

Conversions run in the background of the tab and can be cancelled mid-way if you change your mind.

Supported formats

The converter reads most common audio and video files and exports to any of the formats below.

Video formats

  • MP4 Most compatible container. Works everywhere. With fast-start for quick web playback.
  • MOV QuickTime container. Same structure as MP4 — fast remuxing.
  • MKV Matroska. Flexible container used by many sources.
  • WebM Web-native format, great for online video with VP8 / VP9 / AV1.

Audio formats

  • MP3 Universally supported. Good pick for podcasts and music sharing.
  • M4A / AAC AAC audio in an MP4 container (M4A) or raw AAC stream (ADTS). Common on Apple devices.
  • WAV Uncompressed PCM audio. Great for editing workflows.
  • OGG Open-source container, usually with Opus or Vorbis audio.

Dedicated one-click pages with format-specific guidance for the most common jobs.

Frequently asked questions