API Tool Calls

Trim, join and resize video

Add clips, set each clip's in and out times, put them in order and choose a social shape. Export one video with Fit bars or a Fill crop.

Free, no sign-up — your video never leaves this browser. Nothing is uploaded.

1. Add your clips

The local video engine (about 0.48 MB) loads only after you add your first clip. Export needs a current browser with WebCodecs. Download before closing this tab.

    3. Output shape and sound

    Burned-in captions

    Times refer to the joined, trimmed timeline before cuts. Each cue wraps to at most two lines. Overlapping cues stack. The small preview shows the current frame and captions; exported captions and downloaded SRT follow silence cuts.

    Silence cutting

    Audio is analysed locally in 20 ms windows. Silence cutting cannot be used with muted exports.

    Social shapes export at 30 fps. Original uses the first clip's size (rounded to even pixels) and frame rate. All clips share that output size and frame rate.

    Choose or drop MP4 / MOV clips to start.

    0% · Ready

    MP4 when H.264 and AAC encoders are available; WebM otherwise.

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    Engine versions, licences and measurements

    Frequently asked questions

    Which video formats can I use?

    Open MP4 and MOV clips with H.264 video and AAC or Opus audio. Trim, join and resize them locally. Your video never leaves the device, and nothing is uploaded. HEVC works where your browser and device can decode it. If your browser cannot read that phone video, the tool explains why. Try Safari or save an H.264 version.

    Why are long videos slow on phones?

    Every frame is decoded, scaled and encoded on your device. Long videos use time, battery and memory, especially on phones. Jobs above 10 minutes or 2 GB show a warning; you can still continue.

    Why do I sometimes get WebM instead of MP4?

    MP4 needs an H.264 video encoder and an AAC audio encoder. If your browser lacks either, the tool uses VP9 and Opus in WebM and explains the choice. Muted MP4 needs only H.264.

    How do I add burned-in captions?

    Load or paste SRT or WebVTT for the joined, trimmed timeline. Choose position, size and style, and shift the times for sync. Captions are drawn onto the exported video locally. You can also download the shifted SRT; it follows cuts when silence cutting is enabled.

    How does silence cutting work?

    The browser analyses audio in 20 ms windows and removes quiet sections meeting your threshold and minimum length. Padding keeps some sound around speech, and 5 ms fades soften cut edges. The page shows how many parts and seconds will be removed before export. Video, audio and captions follow the same cuts. Turn off Mute audio to use it.

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