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Lossless Video Cutter

Cut a selected range from a video without uploading or re-encoding it.

View on GitHub
Local processing
About your filesFiles and content selected in this tool are processed in your browser and are not uploaded to a Browser Kitty backend.
Operation demo See the basic workflow in a short video.

About this tool

Lossless Video Cutter trims a selected range from a video entirely in the browser. It stream-copies compressed video and audio instead of encoding them again, avoiding an additional generation of quality loss and usually finishing much faster than a full transcode.

A thumbnail timeline helps you choose start and end points, and audio can optionally be removed. The selected video is not uploaded to Browser Kitty; the bundled FFmpeg WebAssembly runtime performs the operation locally.

Good for

  • Extract only the useful section of a long video without another quality-lossy encode
  • Quickly remove unwanted beginnings or endings from phone videos
  • Trim large videos without sending them to an online editing service

What it can do

Key capabilities available in this tool.

How to use

  1. Open the tool and choose an MP4, MOV, MKV, WebM, or other supported video.
  2. Set the range to keep with the S/E handles on the thumbnail timeline or by entering times.
  3. Enable audio removal if you want a silent result.
  4. Start the cut and wait for local processing to finish.
  5. If the start point was adjusted to a keyframe, review the details, choose a filename, then save or share the result.

Supported

  • Input containers: MP4 / M4V / MOV / MKV / WebM
  • Video and audio are normally stream-copied without re-encoding
  • A thumbnail timeline is available when the browser can preview the source format
  • The output file is assembled in browser / Emscripten memory before saving

Limitations and notes

  • Lossless cutting does not guarantee an arbitrary exact first frame; H.264/HEVC sources may start at an earlier decodable keyframe.
  • Some unusual codec/container combinations can fail during stream copy or remuxing.
  • Preview availability depends on the browser's native codec support.
  • Very large outputs can consume substantial device memory because the completed file must be held before saving.

Frequently asked questions

Is the video really not recompressed?

For normal cuts, the app copies the compressed video and audio streams without re-encoding, avoiding an additional generation of quality loss.

Why can the actual start differ from the time I chose?

Inter-frame codecs often need the output to begin at a decodable keyframe. The app reports the actual start when such an adjustment occurs.

Is my video uploaded to a server?

No. Loading, range selection, FFmpeg processing, and output generation take place in the browser.

Offline version and source code

The standalone HTML bundles the FFmpeg JavaScript/WebAssembly runtime and can be kept for offline use in a compatible browser.

View source on GitHub

Use together

Useful next steps and companion tools, organized around the workflow.

Inspect first Media Inspector Inspect codecs, FPS, audio, and other details before cutting. Compress next Video Compressor After cutting only the part you need, reduce the file size further. Make an animation Video to GIF / WebP Turn a short scene into an animated GIF or WebP.