BYTETOOLS

Merge Videos (Joiner)

Merge multiple videos into one MP4 online, free. Join clips with different sizes and formats in order — processed in your browser, never uploaded.

Drop video clips here or click to browse (in playback order)Up to 10 clips. Everything is processed locally and never uploaded.

What is the Merge Videos (Joiner)?

The ByteTools Merge Videos tool joins two or more clips into a single MP4, in exactly the order you set.

  • Joins up to 10 clips of mixed resolutions and formats
  • Automatic scaling, letterboxing and frame-rate matching
  • Drag-free reordering with Up/Down buttons
  • Landscape, vertical 9:16 and square output presets
  • 100% local processing — clips are never uploaded
  • Free, watermark-free MP4 output

How to use the Merge Videos (Joiner)

  1. 1

    Drop two or more video clips onto the box, in any order.

  2. 2

    Arrange them with the Up, Down and Remove buttons until the playback order is right.

  3. 3

    Pick an output size, and untick Include audio if one of the clips is silent.

  4. 4

    Click Merge videos, then preview and download the combined MP4.

About the Merge Videos (Joiner)

The ByteTools Merge Videos tool joins two or more clips into a single MP4, in exactly the order you set. Unlike simple joiners, it normalises every clip first — scaling to a common resolution, letterboxing where needed and matching frame rates and audio formats — so videos from different phones, cameras and apps combine without errors.

Use it to stitch parts of a screen recording back together, combine phone clips into one shareable video, assemble a highlight reel or join lecture segments. Reorder clips with the Up/Down buttons before merging, and choose a landscape, vertical or square output size.

All of it happens 100% locally in your browser through a WebAssembly build of ffmpeg. Your clips are never uploaded to any server — there are no accounts, no queues and no watermark — so private footage stays on your device and the only limit is your computer's own memory and patience.

Frequently asked questions

How do I combine multiple videos into one?

Add your clips to this tool, put them in order with the Up and Down buttons, pick an output size and click Merge videos. The tool joins them into a single MP4 entirely inside your browser and gives you a download.

Can I merge videos with different resolutions or formats?

Yes — that is exactly what this tool is built for. Every clip is scaled to the output size you choose, padded with black bars if its shape differs, and converted to a common frame rate and audio format before joining, so mismatched clips still merge cleanly.

Why did merging fail with an audio error?

Usually one of the clips has no audio track, which breaks audio joining. Untick the “Include audio” option and merge again — you will get a clean silent video, and you can add a soundtrack afterwards with the Add Audio to Video tool.

How many videos can I join at once?

Up to 10 clips per merge. Because everything is processed in your browser's memory, joining many long, high-resolution clips can be slow — for big projects, merge in batches of a few clips at a time.

Are my videos uploaded while merging?

No. The merge runs locally with a WebAssembly build of ffmpeg, so your clips never leave your computer. There is no server, no account and no watermark on the result.

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