What if the clips have different sizes?

Letterbox keeps every frame whole and fills the rest with black bars. Crop to fill zooms in and trims the edges so the picture fills the frame with no bars.

Why is it slower than a desktop editor?

FFmpeg runs single-threaded in the browser and merging re-encodes every clip. A few short clips usually take a minute or two; long videos take longer.

Are my files uploaded to a server?

No. Everything runs locally in your browser via WebAssembly. Files never leave your computer and are discarded when you close the page.

Do I need to sign up or pay?

No. The site is completely free, requires no account, has no usage limits and adds no watermarks.

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🧩Merge Videos Online - Join Multiple Clips into One File

Join several clips into one MP4, in the order you arrange them. The clips can have completely different resolutions, frame rates and formats — the sizes are unified automatically. Clips without an audio track get silence added, so the second half never ends up mute.

Free · No sign-up · Runs in your browserLast updated: 2026-10-26

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How to use Merge Videos

1Upload two or more videos and reorder them with ↑↓
2Choose how to handle different frame sizes, plus output resolution and quality
3Click start and download the merged video

FAQ

What if the clips have different sizes?: Letterbox keeps every frame whole and fills the rest with black bars. Crop to fill zooms in and trims the edges so the picture fills the frame with no bars.
Why is it slower than a desktop editor?: FFmpeg runs single-threaded in the browser and merging re-encodes every clip. A few short clips usually take a minute or two; long videos take longer.
Are my files uploaded to a server?: No. Everything runs locally in your browser via WebAssembly. Files never leave your computer and are discarded when you close the page.
Do I need to sign up or pay?: No. The site is completely free, requires no account, has no usage limits and adds no watermarks.