toolkitta.
Local file processing

Merge Video

Put clips in order and join them into one MP4. Compatible matching streams can be copied without re-encoding; different clips are encoded into one frame size.

Your videos are never uploaded

Use this focused tool, then choose Edit in editor to carry originals and settings onto the timeline.

  • Clip order & transitions
  • No uploads · Preview before downloading
About Batch and Interactive Editor

How to use Interactive Editor

  1. Open Batch originals as a sequence, or choose Edit in editor to also carry your current settings.
  2. Select a clip to trim, split, slip, set speed, frame the picture or mix its sound. Add tracks, titles, images and music; Undo keeps changes reversible.
  3. Export MP4/WebM or explicitly save a project to keep originals and tracks editable. A recipe repeats the arrangement in either workflow mode.

Mode switching resumes independent sessions. Editor output uses one frame size up to a 1,920 px longest side / 30 fps, and re-encodes frames. Batch retains its existing fast operations and limits. Trim/Crop Batch still edit one video at a time.

Editor limits: 20 sources / 1 GB total, videos up to 500 MB and 15 minutes each, audio up to 50 MB / 15 minutes, 30-minute output. Saved projects include originals and their metadata. Recipes contain only settings and generic source slots; nothing is saved automatically.

How it works

How to merge videos in Batch

  1. Add two or more videos: MP4, MOV, MKV or WebM, up to 20 clips and 500 MB each.
  2. Drag the clips into order or use their Up and Down buttons; the timeline shows each clip's share of the result. Tap Trim on a clip to keep only part of it.
  3. Keep the first clip's shape or choose 16:9, 9:16, 1:1 or 4:5. For clips of another shape, choose Fit for black bars or Fill to fill the frame. Use Also to resize, add music, compress or remove the sound in the same pass, then click Merge videos, play the result and download it.

Join landscape and portrait clips with Fit or Fill

Add a landscape clip followed by a portrait clip, keep Shape set to the first clip and compare Fit with Fill. Fit keeps the portrait picture with black bars; Fill crops its edges to fill the landscape frame. Check that faces and text remain visible.

For public practice inputs, download the 12-second synthetic MP4, make a second copy with Crop Video set to 9:16, and add the original and cropped copy here. The sample has labelled moving shapes and a quiet tone.

Use the clips' Up and Down buttons to choose the order, then click Merge videos. Play across the join before downloading. Different frame sizes require a new encode; the page reports when matching streams can be copied instead.

Frequently asked questions

Useful details

7 answers
Can I arrange clips on a timeline?

Yes. Interactive Editor offers tracks, trim/split/slip, per-clip speed, framing, titles and audio mixing. Edit in editor carries Batch originals and settings. Each mode retains its own session.

Can I merge videos with different sizes or orientations?

Yes. The result takes the first clip's shape. A vertical clip in a horizontal video gets black bars with Fit, or is cropped to fill the frame with Fill.

Will the quality drop?

Compatible matching video streams can be copied when your settings leave the picture unchanged. Otherwise the picture is re-encoded at a bitrate suited to its size. Add Resize or Compress for a smaller file. Target size may encode a second pass if the first result exceeds its limit.

Is there a watermark or upload?

No. Your browser reads, joins and saves the video on this device. Nothing is sent to a server, and there is no watermark or account.

Can I add background music?

Yes. Add Music under Also and choose a song. Mix plays it under the clips' own sound; Replace uses it as the only sound. It repeats to the end if you want and fades out as the video ends.

Can I cut the start or end of a clip?

Yes. Tap a clip's Trim button, drag across its filmstrip or use Start here and End here, and only that part is joined. Trimmed clips are re-encoded so each cut lands on the exact frame.

Can I add transitions?

Yes, a fade: turn on Fade between clips for a short dip to black and silence at each join. Without it, clips are joined with straight cuts, allowing compatible matching streams to be copied when no other picture changes are selected. If clips are re-encoded, the page names the clip that caused it.

More help

Guides, common conversions and useful next steps.

Edit the video

Arrange clips, music and titles together on a local timeline.

Continue with your result

Use the action beside a finished result to send it directly, or open another tool: