Merge Videos

Join two or more clips into one file. Clips off one camera usually copy straight through with no quality lost; a mixed batch gets decoded and re-encoded so the join still works. Either way, the tool says which case you're in before you press run.

Why some merges are instant and others aren't

A video track can only carry one format description for its whole length. Mediabunny — the library behind this tool — caches that description off the first clip's packets and reuses it for the rest, so feeding it a second clip in a different format would silently corrupt the output rather than fail loudly. That is the reason this tool has exactly two paths and no in-between: either every clip matches closely enough to copy, or every clip is decoded and re-encoded into a fresh, common format. There is no "re-encode just the odd clip out" — a video track cannot describe two formats at once.

The picture and the sound are judged separately, because they routinely disagree. Clips off one camera copy their frames straight through, but their audio can still differ in sample rate or channel count — a front-facing and a rear-facing recording mode on the same phone is a common way this happens. When that's true, the picture stays a stream copy and only the audio is decoded, matched to one rate and layout, and rebuilt. That is the same three-tier idea behind changing a video's speed: what actually happened to the picture and what happened to the sound are two different facts, and this tool never collapses them into one.

If your clips won't copy and you'd rather they did, the fix is usually converting the odd one out to match the rest first, then merging. That's two tools doing one job each, which is deliberate — a merge tool that also converts formats is an editor, and that's more than this page promises.

Frequently asked questions

How do I merge videos in the browser?

Drop two or more clips in — they append in the order you drop them — drag rows or use the up/down buttons to set the order, choose what happens to the audio, and export. Nothing is uploaded: the whole join happens in this browser tab.

Can I merge clips from different phones or cameras?

Yes, but it costs something worth knowing before you run it. Clips off the same camera usually share a format and join by copying their frames — nothing is decoded, and it finishes in about the time it takes to read the files. Clips from different sources rarely match, and when they don't, every frame has to be decoded, framed to a common size and re-encoded, which takes real time on a long list. The tool tells you which case you're in before you start, per clip.

Does merging re-encode and lose quality?

Only when the clips don't already match. A video track can carry only one format description, so a merge is either a full stream copy or a full re-encode — there is no middle setting that fixes just the odd clip out. When every clip shares a codec, size, colour space and rotation, the picture copies frame for frame with no quality lost. Audio is judged separately: even a picture that copies may need its audio rebuilt if the tracks don't already match, because that is the only way to make the joins land on exact sample boundaries.

Can I merge different frame rates?

Yes, and it isn't the problem it is with some other tools. Frame timestamps are explicit in the file, so a 30 fps clip and a 24 fps clip concatenate into one variable-rate track without a hitch on the copy path — frame rate never blocks a merge here.

Can I merge a video and a separate audio file?

Yes, but on a different page: putting one audio track onto one video is muxing rather than concatenating, so it has its own tool — Add Audio to Video, at /tools/add-audio-to-video. It replaces a video's soundtrack or mixes a new one under it, and copies the picture rather than re-encoding it.

What happens to subtitle tracks?

They're dropped. Only video and audio are carried into the joined file.

How many clips, and how big?

Up to 20 clips, totalling 1 GB. That ceiling is on the sum of the clips, not any one file, because the joined output is built whole in this tab's memory before it downloads — a merge is the one operation here whose output is bigger than its input.

Does anything get uploaded?

No. Every clip is read from disk and joined inside this browser tab — there is no server, no queue, no account and no watermark.

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