Can I merge videos of different sizes or orientations?

Yes. Every clip is drawn onto one frame: the first clip's shape by default, or 9:16, 16:9 or 1:1. Fit with bars keeps each clip whole and adds black bars where the shapes differ; Crop to fill fills the frame and trims the edges. Mixed frame rates and rotated phone clips are handled too.

Is anything uploaded?

No. The clips are decoded, joined and encoded in your browser with WebCodecs. There is no server, no queue, no account and no watermark, and footage you have not published stays on your machine.

Does merging lose quality?

A little. Joining clips that differ in size or codec means re-encoding them, so the tool encodes the result in H.264 at a high bitrate. On a phone screen it is hard to tell apart from the originals. The output is capped at 1920 px on its long side, which every platform accepts.

What happens to the sound?

Each clip keeps its own audio on its own stretch of the timeline. A clip with no sound gets silence for its length, so the audio of the clips after it never drifts out of sync.

How many clips and how big?

Up to 20 clips and 500 MB together, which is about what a browser tab can hold in memory. It works in Chrome, Edge, Brave, Opera and Safari 17 or newer on a desktop, and Chrome on Android. Firefox shows a notice if it cannot encode video yet.

Free Tool

Merge Videos

Join clips end to end into one MP4 in your browser. Mixed sizes, orientations and formats. No upload, no watermark, no sign-up.

Up to 20 clipsMP4, MOV, WebMNo uploadNo watermark

Drop the videos to merge

Two to 20 clips, MP4, MOV, WebM or MKV, up to 500 MB together. They never leave your device.

How clips that do not match become one video

Two MP4 files can only be glued together as they are when everything about them matches: the codec, the resolution, the encoder settings, often down to the frame rate. Clips from different phones, apps or days almost never do. A portrait iPhone clip, a landscape screen recording and a slow-motion shot each need different decoder settings, and a player handed all three in one file stalls or shows garbage.

So this tool decodes every clip, draws each frame onto one canvas at the size you pick and encodes a single new H.264 stream. Each clip's sound is resampled onto the same timeline, and a silent clip gets the same length of silence, so the clips after it stay in sync. The result is one ordinary MP4 that every player, editor and platform opens.

It all happens in the browser with WebCodecs. The clips are read from your disk and the MP4 is built in memory, so nothing is uploaded, nothing waits in a queue and there is no watermark.

Frequently asked questions

Mixed sizes, sound and limits

Drop two or more clips onto the page, put them in order with the up and down arrows, pick the output frame and press Merge. The clips play back to back in one MP4 with their sound, ready to download.

More free tools

Video trimmerCut each clip to the part you want before you join them.

MOV to MP4Convert an iPhone or QuickTime MOV to MP4 in seconds, nothing uploaded.

Video compressorShrink the merged video under a Discord, WhatsApp or email limit.

Video resizerReframe the result to 9:16, 1:1, 4:5 or 16:9.

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