tooloora

Trim Video — cut MP4 & MOV down to the part you need

Set start and end on the timeline, choose fast lossless cutting or a frame-accurate re-encode — locally in your browser, no upload.

Runs locally — nothing is uploaded

Drop a video file here or click

MP4, MOV, WebM or MKV · one file · stays local

Runs locally in your browser – no upload.

Up to 120 minutes per video – longer material exceeds the browser's memory and your patience.

How do I trim a video in the browser?

Drop the file, drag start and end on the timeline or type them as a time, pick the method and export. The fast mode copies the picture data unchanged and finishes in seconds; the exact mode re-encodes the range and hits your mark frame-accurately. Both run locally — the file is never uploaded.

Why does the fast cut not start exactly at my mark?

Because video compression builds frames on top of each other. Only certain frames are independently decodable: in H.264 they are called IDR frames (Instantaneous Decoding Refresh), defined in the standard ITU-T H.264, "Advanced video coding for generic audiovisual services". Everything in between only describes the change from the previous frame and is worthless on its own. A lossless cut can therefore only begin at such a key frame. Cameras typically place one every one to five seconds — the tool reads that grid from your file, draws it as ticks on the timeline and tells you in advance where your cut will really start.

Fast or exact — which should I pick?

Fast, when one or two seconds of lead-in do not matter: no quality loss, seconds instead of minutes, and the file stays exactly as sharp as the original. Exact, when the start has to sit — for instance when a word or a cut must not be clipped. The price: the range is encoded again, so a lossy source goes through a second compression, and it takes roughly as long as the selection.

Can I remove a piece from the middle?

Not in one step. Export the part before and the part after separately. Joining them again needs a tool that merges video — deliberately not offered here yet, rather than offered badly.

Honest limits

The lossless cut may run up to two hours, because it only moves packets around; the exact re-encode is capped at 30 minutes. In fast mode the audio is aligned to the next audio packet, which can shift its start by a few milliseconds. And if your video's codec does not fit losslessly into an MP4 container (VP8 from a WebM file, for example), the tool re-encodes — and says so, instead of claiming "lossless".

Frequently asked questions

Is my video uploaded to trim it?

No. Reading, cutting and writing all happen in your browser. Nothing is transferred — which matters for recordings you would not hand to a random web service, and it also means there is no server-side file size limit.

What is the difference between fast and exact?

Fast copies the existing picture data unchanged into a new container: no quality loss and done in seconds. Exact decodes and re-encodes the selected range, hits your start time to the frame, but costs time and one more round of lossy compression.

Why does the fast cut start earlier than I set it?

Because it can only begin at a key frame. A key frame is a complete picture; the frames between it only describe the change from the previous one and are useless on their own. Cameras place a key frame every one to five seconds, so the tool jumps back to the last one before your mark — and it shows you the exact grid, rather than silently shifting your cut.

Can I cut a piece out of the middle?

Not in one step. Export the part before the unwanted section, then the part after it. Joining the two pieces afterwards needs a tool that merges video, which this one deliberately does not claim to do.

Does trimming reduce quality?

In fast mode not at all — the packets are copied byte for byte. In exact mode the range is encoded once more, so a lossy source goes through a second compression. Use fast whenever the keyframe grid is close enough for you.

How long may the video be?

Up to two hours for the fast, lossless cut, because only packets are moved. The exact re-encode is capped at 30 minutes: every frame goes through the encoder and the tab has to stay open for the whole time.