Video Joiner

About Video Joiner

Joining videos sounds trivial until you try it: drag two MP4s into iMovie, get a half-hour render. Use a 'free' online tool, hit a 100MB cap or a watermark. Open ffmpeg in terminal, fight with concat filters and codec mismatches. This tool solves all three: drag-and-drop multiple MP4/WebM/MOV files (up to 200MB combined), reorder by dragging, then merge — ffmpeg.wasm runs in your browser and stitches the clips into a single seamless video. Because clips often differ in resolution, frame rate and audio, every input is re-encoded and normalized to a common size, 30fps and stereo audio before concatenation — this guarantees a correct merge across mixed sources but is lossy, not a lossless copy. You choose the trade-off: a quality preset (H.264 CRF 18/23/28), a target resolution (Source-Max, 1080p, 720p or 480p) and an optional web-optimized faststart flag. Output is MP4 (H.264 + AAC, universal) or WebM (VP9 + Opus, web-native). Common uses: combining phone clips into a single travel vlog, stitching screen recordings of a tutorial, assembling reaction segments, merging dashcam footage by trip. See also our Compress Video and Video Thumbnail Generator.

What video formats are supported?

You can upload MP4, WebM, and MOV video files. The output can be in MP4, WebM, or match the first video's format.

How do I merge videos?

Click to select multiple video files or drag and drop them. The videos will be merged in the order shown. You can drag videos up or down to reorder them before merging.

What is the file size limit?

The total combined size of all videos should not exceed 200MB. This ensures smooth processing in your browser. For larger videos, consider using desktop video editing software.

Will merging affect video quality?

Yes — this is a re-encode, not a lossless copy. To join clips of different resolution, frame rate or audio, each input is normalized and re-encoded with H.264 (default CRF 23, AAC 192k). Pick the High quality preset (CRF 18) to minimize loss, or Low (CRF 28) for a smaller file.

What codec, bitrate and resolution does the output use?

MP4 output is H.264 video + AAC audio at 192 kbps; WebM output is VP9 + Opus. Quality is controlled by CRF (High 18 / Balanced 23 / Low 28). Resolution follows your preset: Source-Max keeps the largest input dimensions (capped at 1080p), or pick 1080p/720p/480p. Everything is normalized to 30fps and stereo. Enable Web-optimized to add -movflags +faststart so MP4/MOV streams immediately on the web.

Can I merge clips that have no audio (screen recordings, dashcam, GoPro)?

Yes. Clips without an audio track no longer break the merge — a matching silent stereo track is generated for them automatically, so a silent screen recording joins cleanly with clips that do have sound and stays in sync.

Can I merge videos of different formats?

Yes! All videos are automatically converted to the same format during merging to ensure compatibility. You can choose the output format (MP4, WebM, or match first video).

Is my video file safe?

Absolutely! All video processing happens directly in your browser using FFmpeg.wasm (WebAssembly). Your video files are never uploaded to any server. Everything stays private on your device.

Can I preview before downloading?

Currently, preview is shown after merging. You can download the merged video and play it to verify the result.

How long does merging take?

Merging time depends on the total video length and your device performance. Typically, merging 2-3 short videos takes 30-60 seconds. Longer or more videos will take proportionally longer.