How to trim a video
Drop in an MP4, MOV, WebM or GIF and a strip of its frames is drawn. Drag the left handle to where the part you want begins and the right one to where it ends; the play button plays only that part. For an exact cut, type times into Start and End as minutes and seconds, like 1:05.5, or move the playhead and press Start at playhead. Then press Save video.
Cut where you put it
Quick trimmers copy the file and can only cut at a keyframe, which may be a few seconds from where you asked. This one decodes the frames and encodes the kept part again, so the clip starts on the frame you chose. The cost is time: it works through only the part you keep, so keeping 20 seconds of a long film is quick, and keeping all of it is not.
From the keyboard
A focused handle moves a tenth of a second with the arrow keys, a whole second with Shift or Page Up and Page Down; Home and End send it to the ends. On the playhead, Space or K plays and pauses.
Questions
Can I cut a piece out of the middle?
Not in one go: the editor keeps one part, from Start to End. To lose a stretch in the middle, save the part before it and the part after it as two files.
Does trimming lower the quality?
Slightly, since the kept part is encoded again. Move the quality slider toward Sharper for a clip you will edit further; the line under it estimates the file size before you start.
Why won't my video open?
Your browser does the decoding, so the video has to be in a format it knows. H.264, VP8 and VP9 open almost everywhere; H.265 (HEVC) from newer iPhones opens only where the browser can decode it. Firefox cannot encode video yet, so use Chrome, Edge or Safari 16.4 or later.