How to use
- Select or drop a video file (MP4, WebM, MOV or MKV).
- Drag the box to move it, and drag the corner handle to resize the crop area.
- Click “Crop video” and wait for processing — the engine loads on first run only.
- Download the cropped video.
Frequently asked questions
Is my video uploaded to a server?
No. The whole crop runs locally in your browser with ffmpeg.wasm, so your video never leaves your device and nothing is uploaded.
Which video formats can I crop?
You can crop common formats like MP4, WebM, MOV and MKV. The cropped clip keeps the same container as your source — MP4 stays MP4, WebM stays WebM, and so on.
Why is the first crop slow?
The first run downloads the roughly 30 MB ffmpeg engine. After that it is cached in your browser, so later crops start much faster and even work offline.
Is the audio kept after cropping?
Yes. Only the picture is cropped to your selected rectangle; the original audio track is copied through unchanged.
How do I choose the exact crop area?
A frame of your video is drawn onto a canvas so you can drag the box to reposition it and drag the corner handle to resize it. The on-screen selection is mapped back to the real source pixels before cropping.
Is there a file size or length limit?
There is no fixed limit, but because everything runs in your browser, very large or long videos use more memory and take longer. If a big clip struggles, try a shorter or lower-resolution source.
About this tool
Free online video cropper: crop MP4, WebM, MOV or MKV to any rectangle by dragging a box over a preview frame. Runs 100% in your browser — no uploads, audio kept.