Merge videos

Inside a video file, the picture is a series of compressed packets. If every clip was made with the same codec, at the same resolution and with the same encoder settings – say, on the same phone, one after another – those packets can simply be copied end to end, with only their timestamps shifted. That's lossless merging: the original picture and sound go into the finished file bit for bit, and it's done in seconds because nothing has to be decoded.

If the clips differ (another phone, another resolution, one landscape and one portrait, one WebM and one MP4), that isn't possible, because a single video track can't mix different encoder settings. In that case every clip is decoded, fitted to a common size and encoded again into one H.264 MP4. After reading your files, the tool tells you which case applies before you start.

When re-encoding, the output size defaults to the first clip's, but you can also pick 1080p or 720p. Clips with a different aspect ratio get black bars: an upright phone clip inside a landscape video appears in the middle with bars on either side. Nothing is cropped and nothing is stretched.

If you want every clip to fill the frame, first crop them to the same aspect ratio with crop video, or resize them with resize video. Tip: put the clip whose size you want for the final video first in the list, because that's what the output matches by default.

With lossless merging, the audio is copied unchanged too. When re-encoding, each clip's audio is decoded, brought to a common sample rate and encoded to AAC (or Opus where the browser can't encode AAC). If a clip is silent, silence fills its slot, so sound and picture stay in sync all the way through.

Clips recorded on different devices can differ in loudness. We don't level that automatically; if it bothers you, turn the louder clip down first, or even out the finished video's audio afterwards.

• Holidays and family events: lots of short phone clips become one watchable film.
• Split recordings: some cameras and phones split long recordings into 4 GB or minute-long chunks. These usually share the same encoding, so they merge losslessly.
• Tutorials and demos: put separately recorded parts (intro, steps, wrap-up) into one file.
• Social video: build a Reel or TikTok out of several short scenes.
• Screen recordings: join several separately captured screen sessions into one video.

If you only need part of a clip, cut it out first with the video trimmer, then merge it with the rest.

Lossless merging is almost instant, whatever the file size. Re-encoding runs on your device using the browser's built-in video encoder (WebCodecs): on a modern laptop it runs at roughly real time or faster, on a phone more slowly.

The finished video is assembled in browser memory until you download it. On a computer that's usually fine up to a few gigabytes; on a phone, clips of a few minutes adding up to a few hundred megabytes are the safe bet. You can merge up to 10 clips at once; if you need more, merge ten, then merge the result with the next batch.

Your videos are never uploaded: your browser reads them, builds the merged file and hands it to you as a download. No watermark, no sign-up and no daily limit.