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Video converter

Convert video to MP4, WebM or animated GIF — or pull the audio out as MP3/M4A/WAV. Private — no upload

Click to choose or drag & drop a video here

MP4, MOV, MKV, AVI, WebM, WMV, FLV · one file at a time

Notes

How it works: the first time you convert, a ~31 MB video engine (FFmpeg, compiled to WebAssembly) downloads to your browser and is cached — later conversions skip the download. Everything then runs on your device; nothing is uploaded.

Speed: pulling the audio out (MP3/M4A/WAV) is quick. Re-encoding video (MP4, WebM, GIF) is heavier and runs on a single thread here, so a long or high-resolution clip can take a few minutes — a progress bar keeps you posted.

Heads-up: very large files (roughly over 1–2 GB) may run out of browser memory; trim or shrink first if you hit a limit. A desktop browser handles big videos best.

How to use the video converter

  1. Pick the output: MP4 (H.264 — plays practically everywhere), WebM (VP8 — the open web format), animated GIF, or audio-only MP3, M4A or WAV.
  2. Drop in a video — MP4, MOV, MKV, AVI, WebM, WMV, FLV and more, one file at a time. On first use a ~31 MB FFmpeg engine downloads once and is cached for future visits.
  3. Watch the progress bar while it converts on your device. Pulling audio out is quick; re-encoding video takes longer because it runs on a single thread.
  4. Preview the result right on the page — video and audio get a built-in player, GIFs display inline — then click Download.

Common uses

  • Make a phone or camera clip universal: convert an iPhone .MOV or a downloaded .MKV into an MP4 that plays on any device and uploads anywhere.
  • Pull the audio out of a lecture, webinar or concert video as MP3 — or as lossless WAV if you plan to edit it.
  • Turn a few seconds of video into a looping GIF for a README, chat message or bug report.
  • Re-encode a screen recording to WebM for the web, or shrink an oversized camera file — camera footage is lightly compressed and usually re-encodes far smaller.

Tips & limitations

  • Set expectations for speed: the engine is single-threaded WebAssembly, so re-encoding a long or high-resolution video can take several minutes. Audio extraction skips video encoding entirely and is much faster.
  • Everything runs in browser memory, so very large files (roughly 1–2 GB and up) can fail. Trim or downscale first, and prefer a desktop browser for big jobs.
  • GIF suits only short clips. Output is sampled at 12 fps and scaled to 480 px wide, and even then a GIF runs many times bigger than the same clip as MP4 — keep it to a few seconds.
  • Converting re-encodes the video rather than copying it, so there's a small quality cost each time — keep your original. The MP4 output is written with faststart, so it can begin playing before it's fully downloaded when hosted on the web.
  • One file at a time — and download your result before starting the next conversion, because the results area clears when a new run begins. The engine stays loaded, so there's no second download.

How it's built & why it's safe

This is FFmpeg — the open-source engine behind most video software — compiled to WebAssembly (ffmpeg.wasm) and run entirely in your browser, so your video is never uploaded. MP4 output uses the libx264 H.264 encoder with AAC audio; WebM uses VP8 with Vorbis; audio-only output uses LAME MP3, AAC or 16-bit PCM. It's the single-threaded build, which keeps the page working like any other (no special isolation required) at the cost of speed. The small JavaScript glue ships with the site; only the ~31 MB engine binary comes from a CDN and is cached after the first run.

Related tools: Audio Converter · Vocal Remover · Image Converter

Further reading: MP4, WebM or GIF? Picking the right video format · How to extract audio from a video (and which format to pick)

Frequently asked questions

Is my video uploaded?

No. Conversion runs entirely in your browser with FFmpeg compiled to WebAssembly, so your video never leaves your device. The only thing downloaded is the conversion engine itself, once.

Which formats can I convert?

Input can be MP4, MOV, MKV, AVI, WebM, WMV, FLV and most other common formats — anything FFmpeg can read. Output is MP4 (H.264 + AAC), WebM (VP8 + Vorbis), animated GIF, or audio only as MP3, M4A or WAV.

Why is the first conversion slower?

The first time, a ~31 MB video engine downloads to your browser and is cached, so later visits skip it entirely. Re-encoding video is also inherently heavier than extracting audio.

How long does a conversion take?

Extracting audio usually takes seconds. Re-encoding video (MP4, WebM, GIF) runs on a single CPU thread here, so a long or high-resolution clip can take a few minutes — the progress bar shows where it's at.

Is there a file-size limit?

There's no hard cap, but the whole job runs in your browser's memory, so very large files (roughly over 1–2 GB) may fail. Trimming the clip or lowering its resolution first helps, and desktop browsers handle big files best.

Can it make a GIF from a video?

Yes — choose GIF as the output. The video is sampled at 12 frames per second and scaled to 480 pixels wide to keep the file size reasonable; clips of a few seconds work best.

Should I choose MP4 or WebM?

MP4 with H.264 is the safe default — it plays on practically every device, TV and app. WebM is a royalty-free format that works great in browsers but has patchier support elsewhere. When in doubt, pick MP4.