Merge Videos
Combine several clips into one MP4 — reorder them, trim each one, fit them to a vertical, square or wide frame and add smooth crossfades. Free, no watermark, nothing uploaded.
Free · No sign-upHow to use Merge Videos
- 1. Drop two or more videos (MP4, MOV or WebM). Add more at any time with ＋ Add clips.
- 2. Drag the clips into order (or use ◀ ▶), and type a Start and End time on any clip you want to trim.
- 3. Choose the canvas (same as the first clip, 9:16, 1:1, 4:5 or 16:9), how odd-shaped clips fit, the output size and an optional transition such as a crossfade.
- 4. Click Merge videos, watch the progress and Download the MP4. Clips that already match are joined losslessly in seconds.
Frequently asked questions
Is it free, and is my video uploaded?
It is free with no sign-up and no watermark, and nothing is uploaded. The clips are read and joined on your device by ffmpeg compiled to WebAssembly, which downloads once (about 32 MB) and is then cached by your browser.
What is the lossless fast join?
If every clip has the same codec (H.264 or HEVC), size, frame rate and audio format — for example several clips from the same phone — and you keep Same as first clip, Original size, Cut and no trims, the clips are joined without re-encoding. That is much faster and keeps the exact original quality. Otherwise the tool tells you the clips will be re-encoded.
Can I merge clips of different sizes or from different phones?
Yes. Every clip is scaled to the canvas you pick and converted to the frame rate of the first clip. Clips with a different shape are fitted with a blurred background or black bars, or cropped to fill the frame — your choice. The result is an H.264 MP4 with AAC audio at quality level CRF 23.
What happens to clips without sound?
A silent audio track of the right length is added for them, so the sound of the other clips stays in sync. If none of the clips has audio, or you tick Remove audio, the MP4 has no audio track.
How do transitions change the length?
A cut keeps the full length, so clips of 4, 6 and 5 seconds make a 15-second video. Each crossfade, fade through black, slide or wipe overlaps two neighboring clips, so with a 1-second transition the same three clips make 13 seconds. The summary above the Merge button always shows the final length.
Is there a size limit?
There is no fixed limit, but everything is processed in your browser's memory. The tool warns you above about 150 MB in total on a phone or 700 MB on a computer. Re-encoding runs on your own processor, so 720p or 480p is much faster than 1080p, especially on phones.