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Video Merger

Join multiple videos into one — instant stream-copy concat or full normalize to MP4. 100% in-browser.

LOCAL · FFMPEG.WASMAny orderLossless concatMixed sources100% local

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Drop videos here, or click to browse

MP4, WebM, MOV, AVI, MKV (max 500 MB each)

Drop two or more videos, arrange the order, and join them into one file

Data Source & Legal Disclaimer

Effective: 2026Last updated: TodayUpdate: Manual review

Sources: ffmpeg.wasm — Browser-based media processing

Video merging runs entirely in your browser using ffmpeg.wasm. Your video files are never uploaded to any server.

See all data sources & update policy →

How video joining works — illustrated

ffmpeg's concat demuxer reads a playlist file and stitches the clips end-to-end. In fast mode (-c copy) the compressed packets of every clip are copied verbatim into the output — instant and lossless, but only reliable when all clips share the same codec, resolution, and container (typical for segments recorded by one device). Precise mode decodes every clip and re-encodes to a normalized H.264/AAC MP4, which also fixes mixed sources — different phones, screen recordings, or downloads — at the cost of processing time (roughly 0.2× real-time in WebAssembly).

Playlist → concat demuxer → copy (same sources) or normalize (mixed sources)

The concat demuxer splices clips at the packet level. Copy keeps bytes identical; normalize decodes and re-encodes everything to one standard.

Stitching a three-part stream recording — Ana's VOD

Ana records a tutorial in three OBS segments and wants one continuous MP4 for her course.

Queue in order:She drops segment-1 (12.4 s), segment-2 (8.1 s) and segment-3 (15.5 s) and drags them into order — the header shows 12.4 + 8.1 + 15.5 = 36.0 s total
Try fast first:All three came from the same OBS profile, so Fast mode applies: the concat demuxer copies packets end-to-end and finishes in about a second with zero quality loss
Check the seams:She scrubs the 12.4 s and 20.5 s marks where clips join — both transitions are clean, so no re-encode is needed
Mixed sources?:When she later adds a phone clip, the mixed-container warning appears and she re-runs in Precise mode, which decodes everything and outputs one normalized MP4

↩ Back to merger

About this tool

What is this tool?

Join multiple videos into one: lossless concat or normalized MP4. In-browser, free.

Any orderLossless concatMixed sources100% local

What Is the Video Merger?

The Video Merger joins two or more video files end-to-end in the order you choose. It offers ffmpeg's concat demuxer in two flavors: an instant lossless stream copy for same-codec sources, and a full re-encode that normalizes mixed sources into one universal MP4. A live queue shows each clip's size and duration, and the total is computed as clips are added. All processing happens locally in your browser.

How to Merge Videos

Drop your clips (or click to browse — multiple selection is supported), arrange them with the up and down buttons, and pick a merge mode. Fast is instant for matching sources; Precise handles anything but takes a few minutes per minute of video. Click Merge and download the result.

Frequently Asked Questions

When should I use Fast vs Precise merge mode?

Fast mode stream-copies the clips without re-encoding — it is instant and lossless, and works when every clip comes from the same device or export profile (same codec, resolution, and container). Precise mode decodes and re-encodes everything into one H.264/AAC MP4, which is the safe choice for mixed sources like phone clips plus screen recordings.

Why did my fast merge fail?

Stream copy requires compatible codecs across all clips. Mixed containers (MP4 + WebM) or different resolutions usually break it. Switch to Precise mode — it normalizes every clip and always produces a playable MP4.

Are my videos uploaded anywhere?

No. Merging runs entirely in your browser with ffmpeg.wasm. Your files never leave your device, and the tool works offline once the encoder has loaded.