Do all videos need the same resolution?

For best results, use videos with the same resolution, codec, and framerate. Mismatched settings may cause quality issues or playback errors.

What if my clips have different resolutions or codecs?

A fast stream-copy join needs matching codec, resolution and frame rate; mismatched clips can stutter or break playback. The tool detects this and offers to re-encode everything to a common format first — slower, but it produces a clean, seamless result.

Does merging reduce quality?

Not with stream-copy — the streams are copied untouched, so the join is lossless and quick. Quality is only affected when clips must be re-encoded to reconcile different codecs or resolutions before merging.

Why does the audio drift out of sync after merging?

Variable-frame-rate footage, common from phones and screen recorders, has uneven timestamps that accumulate drift across a join. The tool converts VFR to constant frame rate before merging; also make sure all clips share the same audio sample rate.

Can I reorder the clips before merging?

Yes. Add all your clips, then drag them into the sequence you want in the list. The final video plays them back-to-back in that order, so you can arrange intros, segments and outros exactly as needed.

How many videos can I merge at once?

There is no fixed limit, but every clip is loaded into your browser's memory and the output is built locally, so total length and resolution are bounded by your device RAM. Many short clips are fine; several long 4K files are memory-heavy on phones.

Do I need the same frame rate for every clip?

For a seamless stream-copy join, yes — matching frame rate avoids judder and sync issues. If frame rates differ, choose the re-encode option so the tool conforms every clip to one consistent frame rate before joining.

Merge Videos Online — Join Video Files Free

How to use Merge / Join Videos

The Merge Video tool concatenates two or more MP4, WebM or MOV video clips into a single seamless video file — all processed in your browser with no uploads required. Use it to join split recordings, combine multiple scene takes, assemble a highlights reel from separate clips, or stitch back together a video that was split for upload size limits.

Click "Add Video" and select the first clip; repeat to add all the clips you want to merge.
Drag clips in the list to reorder them if needed.
Ensure all clips share the same resolution and codec for a seamless join; the tool will warn you if they differ.
Choose whether to re-encode mismatched clips to a common format or to attempt a stream-copy concat.
Click Merge and download the combined video file.

Your data never leaves your device — 100% private processing.

Stream-copy concat vs re-encode merge

Stream-copy concatenation joins clips without re-encoding, producing lossless output in a fraction of the time. It works only when all clips share identical codec, resolution, frame rate and audio format. If any clip differs in resolution or codec, the output may have stutters, sync drift or playback errors. Re-encoding all clips to a common target format before merging resolves mismatches but is slower. The tool automatically detects mismatches and recommends re-encoding when clips are incompatible.

Keeping audio in sync across merged clips

Audio sync issues are the most common problem when merging clips from different sources. Variable frame rate (VFR) recordings — common on smartphones — can cause gradual audio drift because the timestamps are not uniform. The tool detects VFR footage and converts it to constant frame rate (CFR) before merging to maintain sync. Ensure all clips were recorded at the same sample rate (typically 44.1 kHz or 48 kHz) to avoid resampling artefacts at the join points.

Worked examples

Join three clips

Inputs: Clips of 0:30 + 1:00 + 0:45

Result: 2:15 video

Intro + main

Inputs: 0:05 title card + 4:00 recording

Result: 4:05 video

Glossary

Concatenation: Joining multiple media files sequentially so they play one after the other as a single continuous stream.
Stream copy: Copying media streams from source files to the output container without decoding or re-encoding, preserving original quality.
Variable Frame Rate (VFR): A recording mode where the frame rate can change during capture; common in smartphone screen recordings and can cause audio sync drift when merging.
Constant Frame Rate (CFR): A video mode where every frame occupies the same duration; required for reliable audio sync and stream-copy concatenation.
Audio drift: A gradual misalignment between audio and video tracks that accumulates over time, often caused by mismatched sample rates or VFR footage.

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Merge / Join Videos

How to use Merge / Join Videos

Stream-copy concat vs re-encode merge

Keeping audio in sync across merged clips

Worked examples

Glossary

Related reading

Frequently Asked Questions

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Common use cases

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