Cut an MP4, MOV, WebM or MKV to a shorter clip in seconds, with the original picture and sound untouched. Runs in your browser; nothing is uploaded.
Works on phones for small files; large files need a laptop or desktop. Any input length up to about two hours; the clip itself up to 512 MiB on a desktop, 128 MiB on phones and low-memory devices.
You give it a video and a start and end time. It finds the keyframes closest to those times, copies the packets between them into a new MP4, and gives you the file. Because nothing is decoded or re-encoded, a cut from a ten-minute film takes well under a second once the video has been inspected, and the picture is exactly the original.
The defaults, and why
Any container, any codec. Because packets are copied rather than decoded, the codec does not matter to the cut. MP4 and MOV come out as MP4; WebM stays WebM when its codecs allow it, otherwise the clip is an MKV. Every audio track is kept; subtitle and data tracks are dropped.
Cuts snap to keyframes. A video stream only contains complete pictures at keyframes; every other frame describes a change from the one before. A clip that started between keyframes would open on garbage until the next keyframe arrived, so tools that cut anywhere re-encode the video to create a new keyframe at the cut. That costs minutes and quality. This tool keeps the original encoding and moves the cut instead, and shows you exactly where it moved to before you commit.
The end is exclusive. The last frame included is the one before the snapped end, which keeps clips stackable: trimming 0 to 10 and then 10 to 20 gives you two clips that meet exactly.
Metadata and chapters are dropped. The output carries no title, location, camera or chapter information from the source. If you want the metadata kept, say so; it is a one-line change, and leaving it out is the safer default for sharing.
The file is written for streaming. The index is placed at the front of the file so it plays in a browser before it has fully downloaded.
Limits
- One video track. Cover art is ignored; a file with two real video tracks is refused.
- No limit on the input file’s size. Its length is capped at 200,000 video frames, about two hours at 30 frames per second, because every frame is indexed before cutting.
- The clip is built in the browser’s memory before it can be saved, so its size is the real ceiling: 512 MiB on a desktop, 128 MiB on a phone or a device reporting little memory. A range that would exceed it is refused before any work is done. The desktop app has no such ceiling.
- Audio keeps its own packet boundaries, so the audio can run a few milliseconds past the video at the end of the clip. Players handle this; it is how every stream-copy tool behaves.
- Files whose first frame is not a keyframe, or with unusual timing (open GOP, edit lists), are refused rather than trimmed wrongly.
On a phone
The engine is a 31 MiB download on the first visit, cached afterwards. Phones can trim clips up to 128 MiB; the tool says so before starting rather than running out of memory halfway.
How it was tested
Measured on a ten-minute, 116 MiB H.264 film: indexing in about a second, the verified cut in under a tenth of a second, and every copied packet’s hash matched the source. The same film re-wrapped as WebM (VP9 and Opus) and MKV, an HEVC encode, and a 40-minute, 463 MiB version producing a 349 MiB clip all cut the same way.
Questions
Why did the cut land a little before or after the time I typed?
The cut snaps to the nearest keyframe, because only a keyframe can start a clip without re-encoding. The table shows the exact positions before you trim, and the shift is usually under two seconds.
Does the quality change?
No. The video and audio packets are copied byte for byte into a new file. The tool checks every copied video packet against the source before offering the download.
Which files work?
MP4, MOV, M4V, WebM and MKV, with any video codec (H.264, HEVC, VP8, VP9, AV1 and others) and any number of audio tracks. The clip keeps the same container family as the source. Files whose video uses open GOPs, where frames borrow from pictures outside their own keyframe group, are refused rather than cut wrongly.
Why is there no preview for some files?
The preview uses your browser's own decoder, and browsers only decode some codecs: HEVC plays in Safari and some Chrome builds, MKV files play in Chrome but not Firefox. When the browser cannot show the picture, the cut still works exactly the same; you use the keyframe ruler and the times instead.
Is my video uploaded?
No. The trimming program runs inside your browser tab. You can watch the network panel of your browser while it works, or switch the connection off after the engine has loaded.
How every tool here keeps your files on your device.