Video trimmer — cut MP4, MOV and WebM clips without uploading

How to use the video trimmer

1. Drop a video onto the box or click to choose one. A timeline with the soundtrack’s waveform appears.
2. Drag the start and end handles, or type times into Start and End in seconds (End 0 means “to the end”).
3. Press Play selection to preview.
4. Choose a Cut mode: Fast (no re-encode) or Frame-exact.
5. Pick an Output format (same as the original, MP4, WebM, MOV or MKV), press Trim video and download the clip.

What it does and when to use it

The trimmer keeps one section of a video and removes everything before and after it. Use it to cut a highlight from a phone recording, remove the fumbling at the start and end of a screen recording, shorten a clip to fit a social media length limit, or pull one answer out of a recorded meeting.

Most of the time Fast mode is the right choice: it finishes in seconds even for long files and keeps the original quality, because the picture is not compressed again. Choose Frame-exact for clips where the opening frame matters, such as a reaction shot or a clip that must line up with music.

After trimming, the video compressor can shrink the clip for sharing, the video to GIF converter turns a short moment into an animation, and the video to audio extractor saves just the sound.

How it works

The tool runs in a Web Worker using Mediabunny, an open-source library for reading and writing MP4, MOV, WebM and MKV files (about 0.7 MB, loaded the first time you use a video tool).

• Fast reads the compressed video and audio packets in your range and writes them into a new file unchanged. The start is moved back to the previous keyframe so the clip plays correctly.
• Frame-exact decodes the frames with your browser’s WebCodecs video decoder, drops everything before your start time, and encodes the rest again (H.264/AVC is preferred for MP4, VP9 for WebM, when available).

The result shows the range, the clip length and the original length.

Examples

A highlight from a phone video. Start 12, End 42, Fast mode. You get a 30-second clip from 0:12 to 0:42, copied without re-encoding; the first frame may be a little before 0:12.

A precise clip. Start 5.5, End 9.25, Frame-exact. You get a 3.75-second clip that begins exactly at 0:05.50, re-encoded.

Limits and tips

• One section at a time. To remove a middle part, trim the two pieces you want and join them with the video merger.
• Re-encoding needs WebCodecs. Frame-exact mode needs a current desktop Chrome, Edge, Firefox or Safari, or Chrome on Android.
• Changing format in Fast mode copies the streams when their codecs suit the new container (for example H.264 into MOV). If they do not, the video has to be re-encoded, which is slower; “Same as the original” avoids this.
• Keep the original until you have checked the trimmed clip.