Merge Videos Online

Combine clips into one video

Separate video clips are common when recording tutorials, phone footage, product demos or quick social updates. You may have an intro, a main segment and a short ending, or several camera takes that should play as one file. This merger lets you choose two or more videos and create a single MP4 download without opening a full video editor or uploading private footage to an online service.

The tool runs entirely in the browser. Each selected video is written into ffmpeg.wasm's temporary file system, a concat list is created locally and ffmpeg produces one output file. The source clips and the merged result stay on your device. That is useful for internal demos, support recordings, personal clips and drafts that should not leave your computer just to be stitched together.

Order and compatibility

Files are merged in the order provided by the file picker or drop operation, so choose them in the sequence you want the final video to play. The tool re-encodes the merged result for safety rather than simply copying packets. Re-encoding is slower, but it improves compatibility when the input videos have different codecs, bitrates or audio settings. For best results, use clips with similar frame sizes and orientations.

Browser memory notes

Merging can use a lot of memory because multiple input files and the output are handled locally. Short clips work best. Long high-resolution videos may take time or fail if the browser cannot allocate enough memory. The first merge may also pause while the WebAssembly engine downloads, but later work in the same tab can reuse it. Always keep the original clips until you have checked the merged MP4 from beginning to end.

Tips for clean results

The merged file is encoded as H.264 at CRF 23 with AAC audio at 160 kbps, packaged as MP4. Every clip is joined with ffmpeg's concat method and then re-encoded as a whole. That works best when every clip has the same resolution and frame rate; if they differ, the output may use the settings of the first clip, and clips with other dimensions can look wrong or be rejected by ffmpeg.

Before merging, rotate or resize mismatched clips with the other tools on this site so they share the same orientation and width. A clip with no audio track can also cause trouble when mixed with clips that have sound, so add silent audio or remove audio from all of them beforehand. Because file names are placed in a concat list, the tool gives each clip an internal name, so unusual characters in your original file names are not a problem. Finally, total size matters: the sum of all inputs plus the output must fit in browser memory, so merge a few short clips at a time.