Merge / Join Videos
Upload up to 5 video files to merge them into a single video — processed locally in your browser.
All processing happens in your browser — your files are never uploaded.
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.
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.
Related reading
Frequently Asked Questions
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Why use Merge / Join Videos?
- Powered by FFmpeg running directly in the browser — no upload needed
- Supports all major video and audio formats
- Lossless and lossy options for quality control
- Export results immediately without waiting for cloud processing
Common use cases
- Compress a video before uploading to Google Drive
- Extract audio from a video lecture for easy listening
- Trim a video clip for a social media reel
- Convert MOV files to MP4 for cross-platform compatibility
- Merge two audio tracks for a podcast episode
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