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Video

Merge Video

Combine multiple video files into a single output. Reorder clips, trim each segment, mute audio, and export to MP4 or WebM directly in your browser.

Read the full guide

Practical guide

Merge Video stitches several local video files into a single MP4 or WebM. Clips are decoded, redrawn onto a shared canvas at one resolution and frame rate, optionally crossfaded at each cut, then re-encoded by the browser. After merging, you may want to compress the result if the combined file is too large for upload.

Example preview

Visual examples show the kind of input and output this tool is designed around.

Several clips into one merged file

Drag clips into order, set per-clip trim, then export one MP4 with a crossfade at each cut.

Before
Merge Video demo showing three queued clips combined into a single MP4 timeline with crossfades before
After
Merge Video demo showing three queued clips combined into a single MP4 timeline with crossfades after

Where this fits

Assemble social media compilations

Combine several short clips into a single timeline for posting. After merging, crop the output to a vertical or square aspect ratio if the platform requires it.

Join multi-take recordings

Stitch lecture segments, interview answers, or product walkthroughs that were captured in separate takes. Use crossfade for smoother transitions between clips.

Build a rough cut before editing elsewhere

Combine the keepers from a shoot into one file, then hand it to a full editor. Trim each clip before merging to cut out unusable sections early.

How to use Merge Video

  1. 1Add video filesDrop or browse for up to 30 clips. MP4, MOV, MKV, WebM, AVI, FLV, and WMV are accepted, with a 4 GB per-file limit. Drag the grip handle to reorder clips in the timeline.
  2. 2Set merge optionsChoose MP4 or WebM output, video quality (720p / 1080p / 4K), audio quality, and crossfade duration. Enable Normalize Audio when clips were recorded at different volumes.
  3. 3Merge and downloadClick Merge Video to start encoding. Progress reflects normalize, video, and audio passes combined. Download the result or click Merge another to start over.

Practical notes

Trim clips before merging

Use the per-clip trim panel (scissors icon) to cut out dead air, false starts, or unwanted sections. Only the trimmed range of each clip enters the merged output.

Letterboxing is intentional

When clips have different aspect ratios, the widest source defines the canvas. Narrower clips get black bars rather than being cropped or stretched, which preserves framing.

Chromium browsers offer the widest codec support

The encoder uses the WebCodecs API. DRM-protected files, exotic codecs the browser cannot decode, and files exceeding available RAM may not merge reliably.

Multi-clip video workflow

Trim individual clips first, merge them into one timeline, then compress and finalize the output.

  1. 1

    Video Trimmer

  2. 2

    Merge into one video

  3. 3

    Video Compressor

  4. 4

    Add Subtitles to Video

  5. 5

    Video Thumbnail Generator

Questions worth checking

Are my videos uploaded to a server?

No. Every clip is read, decoded, mixed, and re-encoded inside your browser using Mediabunny and the WebCodecs API. The files never leave your machine.

How many clips can I merge at once?

Up to 30 clips per session, with a 4 GB per-file limit. Very long timelines benefit from a desktop with a hardware video encoder.

Why do my clips look letterboxed in the result?

The encoder writes a single canvas size for the whole timeline. When clips have different aspect ratios, the wider source defines the canvas width and narrower clips are fitted with black bars.

What does Crossfade do?

It overlaps the tail of one clip with the head of the next for the chosen duration. Both video frames are alpha-blended and the audio is fade-out/fade-in mixed across the same window.

When should I turn on Normalize Audio?

Use it when clips were recorded with very different volumes. The tool measures peak amplitude per clip and applies a gain so the loudest sample sits near 0.95, clamped between 0.5x and 8x.

Why did the merge fail with a codec error?

This happens when the browser cannot encode the chosen codec at the requested resolution. Try a smaller quality preset, switch between MP4 and WebM, or use a Chromium-based desktop browser.

Related tools

Video TrimmerTrim and cut video segments by start and end timestamps directly in your browser.
Video CompressorCompress MP4, WebM, MOV, and MKV in your browser. Hit a target file size with H.264, H.265, or AV1, downscale resolution, drop frame rate, strip audio, and preview the result before download.
Split VideoSplit one video into multiple clips by markers, duration, count, or custom ranges, then export selected segments as files or a ZIP.
Add Subtitles to VideoAdd subtitles (SRT, VTT) to your video easily. Customize font, size, color, position and style, then burn them directly into MP4.
Crop VideoCrop unwanted areas from your video. Pick an aspect ratio, drag the crop box, and export an MP4 directly in your browser.
Video Thumbnail GeneratorExtract high-quality thumbnails from video files at custom intervals, timestamps, or counts directly in your browser. Convert video to image snapshots for previews, covers, and social media.