Merge Videos
Add your clips, drag them into order and join them into one MP4. Clips with different sizes or frame rates are fitted to one frame, with black bars or a crop, your choice.
- Nothing is uploaded
- Free, no sign-up, no watermark
- Works offline once loaded
Drop your videos here
or choose files, or paste
MP4, MOV, WEBM, MKV, AVI, M4V, 3GP, FLV, WMV and more. Up to 20 files.
Processed on your device. Nothing is uploaded.
How to use Merge Videos
- 1
Add your clips
Drop two or more videos on the drop zone, or add them one by one. Up to 20 clips are supported.
- 2
Put them in order
Drag the clips in the list into the order they should play, or use the arrows. Remove any you added by mistake.
- 3
Choose the frame
Set Output size (Same as the first clip, or a fixed landscape, vertical or square size) and When sizes differ: Fit with bars or Fill and crop.
- 4
Merge and download
Press Merge videos, watch the progress, then preview and Download the joined MP4.
Why use Aback Video for this
Mixed sources welcome
Clips from different phones and cameras, with different sizes, frame rates and formats, are matched to one frame and one frame rate.
Drag to reorder
Arrange clips in any order before merging. The list shows each clip's length and size.
Bars or crop
Choose whether mismatched clips keep their whole picture with black bars or fill the frame with a crop.
Private by design
All clips are joined in your browser. None of them is uploaded.
Frequently asked questions
Can I merge videos with different formats or sizes?
Yes. MP4, MOV, WebM, MKV and more can be mixed. Every clip is scaled to the output size and converted to the same frame rate, so the result plays smoothly.
What if a clip has no sound?
Silence is added for that clip so the audio stays in sync with the following clips.
Why is merging slower than trimming?
To join clips with different settings reliably, each one is re-encoded to H.264. FFmpeg runs on one thread in the browser, so the total time is roughly the length of all clips together on a recent computer, longer on phones.
Which output size should I pick?
Same as the first clip is right when your clips come from the same device. If you mix vertical phone clips with landscape footage, pick the shape you will post in, such as 1080 x 1920 for Reels.
Are my clips uploaded?
No. Everything happens on your device with FFmpeg compiled to WebAssembly. The page never sends your files anywhere.
Is there a size limit?
There is no fixed limit, but the browser has to hold the output in memory. On a computer several gigabytes of input usually works; on a phone keep the total to a few hundred megabytes.
Can I add a transition between clips?
Merge joins clips with straight cuts. To soften the start and end, run the result through Fade In and Out.