Mix different video sizes
Use one output canvas for landscape, portrait, or other source dimensions instead of preparing every clip first.
Private local processing • No upload • Works in your browser
Merge Videos
Merge multiple video files with different dimensions into one MP4 file in your browser. Choose an output size, fit mode, and whether to keep audio.
What this video merger does
This tool combines two or more video files into one MP4 file. It decodes each clip, converts frames to one selected output size, and places the clips in the order shown on the page. The processing runs locally in your browser.
How to merge videos
- 1.Add at least two video files that your browser can read
- 2.Move clips up or down until the playback order is correct
- 3.Choose the output size and decide whether to contain, cover, or stretch each frame
- 4.Keep audio when the source audio tracks use the same channel count and sample rate
- 5.Start the merge and download the generated MP4 file
Why merge videos in your browser
Control the playback order
Reorder the selected clips before processing so the output follows the sequence you need.
Process files locally
The merge runs in the browser with local media processing, so the selected videos are not sent to a merge server.
Choose how frames fit
Contain keeps the full frame with possible letterboxing, cover crops to fill, and fill stretches to the selected dimensions.
Video merger FAQ
Can I merge videos with different dimensions?
Yes. Choose an output size and a fit mode. Each clip is decoded and resized into the same output canvas before encoding.
What format does the merged video use?
The first version exports one MP4 file using browser video encoding. The result is re-encoded, so this is not a lossless container-only join.
Can I keep audio from the source videos?
Yes, when the source audio tracks use the same channel count and sample rate. You can also turn off audio to create a video-only output.
Are my videos uploaded during the merge?
No. The page passes the selected files to local browser processing and does not upload them to a merge service.
Why might a merge fail in my browser?
The browser must support the required WebCodecs decode and encode paths for the selected files. Large or high-resolution clips also require enough local memory and processing capacity.