Video Trimmer

What this tool does

Video Trimmer keeps just the part of a video you need. Fast mode copies the original audio and video streams into a shorter file in seconds with no quality loss, while Precise mode re-encodes to H.264 MP4 so the cut lands on exactly the frame you chose.

Phones and screen recorders capture far more than you need: the fumble before you start talking, the long pause at the end, the moment you reach to stop recording. Uploading a 2 GB file to an online editor just to cut ten seconds off each end is slow and puts private footage on someone else’s server.

This trimmer runs FFmpeg compiled to WebAssembly on your own device. In Fast mode it uses stream copy: the compressed video and audio packets are written into a new file untouched, so a 20-minute clip is trimmed in seconds and the picture is bit-for-bit identical. Compressed video can only start cleanly on a keyframe, so Fast cuts may begin slightly before your chosen start. Precise mode decodes and re-encodes the segment to H.264 and AAC with a quality level you choose, so the first frame is exactly the one you marked.

How to use Video Trimmer

1. Drop your video onto the upload area or click to browse.
2. Play the preview, pause where the clip should begin and click “Set start to current time”.
3. Pause where it should end and click “Set end to current time”, or type both times in seconds in Settings.
4. Click Play selection to check the range.
5. Choose Cutting mode: Fast for speed and original quality, Precise for frame-accurate cuts (and pick a quality).
6. Click Trim video, then preview and download the result.

Tips for better results

• Phone videos usually have a keyframe every one or two seconds, so Fast cuts are rarely more than a second off.
• Use Precise mode when the start matters, such as cutting a clip that begins mid-sentence.
• CRF 18 to 20 in Precise mode is visually indistinguishable from the source for most footage.
• Fast mode keeps the original container: an MKV stays MKV and a WebM stays WebM.

Common use cases

• Removing the dead time at the start and end of a phone recording before sharing it.
• Cutting a highlight out of a long webinar or lecture recording.
• Making a short clip from a screen recording for a bug report.
• Preparing a 60-second segment to post as a short-form video.

Common mistakes to avoid

• Expecting a frame-exact start from Fast mode: it starts at the nearest earlier keyframe.
• Entering an end time beyond the video length; it is clamped to the end automatically, so check the selection summary.
• Re-encoding several times in a row; each Precise pass loses a little quality, so trim once from the original.