Free Online MP4 Joiner

• An MP4 joiner with a full editor behind it

  Most joiner tools glue clips together and stop there. EchoWave puts your MP4s on a multi-track timeline, so after joining you can crop, rotate, add a title card, or layer a logo over the whole cut before exporting one file. Nothing needs a second tool or a second upload.

• Trim each clip before it joins the cut

  Shave dead air off the start and end of every clip right on the timeline. If a clip needs mid-section surgery, the video cutter removes chunks from the middle and the split tool breaks one file into several, all inside the same project.

• 56 transitions between clips

  Hard cuts suit tutorials, but montages read better with movement. Pick from 56 transitions, adjust how long each one runs, and use automatic beat detection to snap your cuts to the beat of a music track.

• Mix MP4 with MOV, MKV, and 17 other formats

  The joiner accepts 20 video input formats, so a phone MP4, a GoPro MOV, and an OBS MKV can sit in the same sequence and still export as one clean MP4. For standalone format changes, the video converter handles 176 conversion pairs.

• Auto captions across the whole joined video

  Once the clips are merged, one click transcribes the entire cut with word-level timestamps, and the spoken language is detected automatically. Style the result with 176 caption presets or, on Pro, translate the subtitles into 86 languages.

• Music, voice over, and sound effects

  Joined clips usually need connective audio. Lay a music track under the full sequence, record a voice over in the built-in recorder, or generate one with 63 AI voices. A categorized panel of 2,500+ sound effects covers the whooshes and clicks.

• Keep the joined file a sane size

  Merging five clips can produce a heavy file. Set resolution, bitrate, and codec at export time, or run the finished video through the video compressor to squeeze under an upload limit without a visible quality drop.

• Resize the join for any platform

  Landscape and portrait clips can share one canvas thanks to five fit modes, including blurred bars for mismatched aspect ratios. Export the joined video at 9:16 for Shorts and Reels, 1:1 for feeds, or 16:9 for YouTube.

1. 1

   Upload your MP4 files

   Drag your clips into EchoWave from any modern browser on Mac, Windows, Linux, or a Chromebook. MOV, MKV, WebM, AVI, and 15 other formats are accepted alongside MP4, so mixed sources are fine.

2. 2

   Arrange the clips in order

   Each upload lands on the magnetic timeline. Drag the clips into sequence and they snap end to end with no gaps or overlaps, so the joined video plays straight through.

3. 3

   Trim, then add transitions

   Tighten the first and last seconds of each clip, then drop a transition between clips where the edit calls for one. This is also the moment to add captions, a music bed, or a title.

4. 4

   Export one MP4

   Pick a resolution and frame rate and render in the cloud, so an old laptop exports as fast as a new one. Free exports are HD 720p MP4 with a small removable watermark badge; paid plans go up to 4K and 8K.

• Rejoin camera-split recordings

  GoPros, dashcams, and drones chop long recordings into chapter files. Drop the chapters onto the timeline in order and export one continuous MP4 nobody has to click through.

• Combine screen recording takes

  Record a tutorial in parts instead of chasing a perfect single take. Cut the fumbles from each segment, join the keepers, and publish one clean walkthrough.

• Build gaming montages

  Line up your best clips from a session, snap the cuts to the beat of your track, and drop a transition where the energy shifts. One export, ready for YouTube or Discord.

• Assemble course lessons

  Merge an intro, the lesson body, and a recap into a single module. Caption the whole thing in one pass for students who watch with the sound off.

• Stitch interview segments

  Join multi-part interview recordings, cut the tangents on the timeline, and hand off one file. Text-based editing lets you remove filler words from the transcript instead of scrubbing waveforms.

• Make travel and family montages

  Phone clips from a trip become one video with a music bed and a few crossfades. Export a single MP4 the group chat can actually play instead of a dump of thirty files.

Based on each tool's public pages as of July 2026. MP4Joiner is the free desktop app from the MP4Tools suite; it copies streams without re-encoding but requires every clip to share the same codec, resolution, and frame rate.