Does merging reduce quality?

Each clip is re-encoded once at CRF 23, which is visually close to the source for sharing. Keep your originals if you plan to edit further.

Why are there black bars?

Clips with a different aspect ratio are padded to fit the output frame instead of being stretched or cropped. Crop the odd clip to the same ratio first if you want edge-to-edge video.

How long can the merged video be?

Browser memory is the limit. A few minutes of 720p is comfortable on a laptop; very long 4K projects belong in a desktop editor.

Can I merge MOV and MP4 together?

Yes. Any mix of MP4, MOV, WebM, MKV and AVI works because every clip is decoded and re-encoded.

Are my videos uploaded?

No. The clips are read into browser memory and processed there. Nothing is sent to Videozify.

Is there a watermark?

No watermark, no account and no limit on how often you use it.

Can I add a transition between clips?

Not yet. Clips are joined with hard cuts, which is what most social edits use.

Can I put music over the merged video?

Merge first, then replace or mix audio in a full editor; the merger keeps each clip's own sound.

What happens to a clip with no sound?

The merger detects it and joins all clips as a silent video instead of failing.

100% free · runs in your browser · no upload · no signup

Merge Videos Online

Drop a file here

Click to browse, or paste a file from the clipboard.

Choose file

A video merger joins several clips end to end into one file. Videozify does it inside your browser: drop two to ten clips, pick an output height, and download one MP4. The clips are scaled to the same size and frame rate so phone and screen recordings line up without black flashes.

How to use merge videos

Drop your clips onto the box above. Add them in the order you want them to play.
Pick an output height. 720p is the fastest and fine for sharing.
Press Merge videos and keep the tab open while the progress bar runs.
Preview the result, then download the merged MP4.

How merge videos works

Most mergers upload every clip to a server, which is slow on a phone connection and means a stranger's machine holds your footage. Here the join runs locally with FFmpeg compiled to WebAssembly, so a ten-clip holiday reel never leaves your device.

Clips from different sources rarely match. An iPhone shoots 1080p at 30 or 60 fps in HEVC, a screen recorder writes 1440p at a variable rate, and a WhatsApp forward is 480p. A plain stream-copy join of those files produces a broken MP4. This tool normalises every clip to the chosen height, 30 fps and yuv420p before concatenating, which is why it re-encodes.

Clips without a soundtrack are handled too: if one input has no audio, the merger retries as a silent join instead of failing.

Everything runs on your device. See also Video trimmer.

At a glance

Property	Videozify
Inputs	2 to 10 clips
Output	H.264 MP4 + AAC
Frame rate	Normalised to 30 fps
Aspect	Letterboxed to the target height
Processing	In your browser

A video merger joins several clips end to end into one file.

Settings explained

Output height decides the frame size every clip is scaled to. Pick the height of your best clip; scaling a 480p clip up to 1080p only makes it bigger, not sharper.

Order is the order you dropped the files. Remove and re-add a clip to move it.

Tips for a clean merge

Trim first, merge second. Cutting the dead air at the start and end of each clip in the video trimmer before joining keeps the finished reel tight and makes the merge faster, because there is less footage to re-encode.

Mixing portrait and landscape clips works, but the output frame has one shape. If most of your clips are vertical phone footage, crop the odd landscape clip to 9:16 first so nothing is letterboxed. If they are mostly landscape, keep the default and accept bars on the vertical ones.

Audio levels often differ between a quiet indoor clip and a windy outdoor one. Run the loud clip through the volume tool before merging, or boost the quiet one, so viewers don't reach for the volume button between scenes.

On phones, close other tabs before merging long clips. Mobile browsers give each tab a limited amount of memory, and a merge has to hold several decoded clips at once.

Frequently asked questions

Does merging reduce quality?: Each clip is re-encoded once at CRF 23, which is visually close to the source for sharing. Keep your originals if you plan to edit further.
Why are there black bars?: Clips with a different aspect ratio are padded to fit the output frame instead of being stretched or cropped. Crop the odd clip to the same ratio first if you want edge-to-edge video.
How long can the merged video be?: Browser memory is the limit. A few minutes of 720p is comfortable on a laptop; very long 4K projects belong in a desktop editor.
Can I merge MOV and MP4 together?: Yes. Any mix of MP4, MOV, WebM, MKV and AVI works because every clip is decoded and re-encoded.
Are my videos uploaded?: No. The clips are read into browser memory and processed there. Nothing is sent to Videozify.
Is there a watermark?: No watermark, no account and no limit on how often you use it.
Can I add a transition between clips?: Not yet. Clips are joined with hard cuts, which is what most social edits use.
Can I put music over the merged video?: Merge first, then replace or mix audio in a full editor; the merger keeps each clip's own sound.
What happens to a clip with no sound?: The merger detects it and joins all clips as a silent video instead of failing.