Video Merger

How to use Video Merger

1. Add your clips in the order you want them.
2. Check they share resolution and frame rate, or expect a re-encode.
3. Merge, then watch the whole result for audio drift.
4. Matching format, resolution and frame rate allows a lossless join.
5. Filename order is not numeric order — check the sequence before merging.
6. Processing runs in your browser; files are never uploaded.

Matching clips join losslessly; mismatched ones must be re-encoded

If every clip uses the same codec, resolution and frame rate, the streams can be concatenated without re-encoding — instant, and no quality lost. Mix a 1080p30 clip with a 720p60 one and everything has to be decoded and re-encoded to a common format, which is slow in a browser and costs a generation of quality. Normalising clips before merging is almost always faster than merging mismatched ones.

Audio is where it goes wrong quietly

Clips with different audio sample rates or channel counts can produce output that drifts out of sync partway through, and a clip with no audio track at all can silence everything after it depending on how the join is done. Check the whole output, not just the joins — sync problems accumulate and are often only obvious several minutes in.

Order and the limits of a browser tab

Clips join in the order given, so check it before merging — filename sorting puts clip10 before clip2, which is the usual cause of a jumbled result. And every clip is held in memory during processing, so merging several large files can exhaust the tab. Trim each clip first: everything downstream runs on less material, and the trade for browser processing is that nothing is uploaded.