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  1. Home
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  3. Merge Videos

Merge Videos

Join compatible clips in selected order with a fast concat path.

Use this tool
Browser-local processingNo input upload to TOOLGRIDReview before copy
Formats and processing
Input
H.264/AAC MP4 video
Output
Merged video file
Runtime
FFmpeg WASM
Browser-local workspaceStart below with browser-local processing.

Tool code processes selected files and entered content in your browser and does not submit them to a TOOLGRID processing endpoint. TOOLGRID measures tool usage, not the content you enter.

Loading tool…

Browser-basedWhat this tool does

Merge two or more local video files in the chosen order. The fast concat path checks compatible containers, codecs, display dimensions, rotation metadata, measured frame-rate estimates, and audio layouts.

Processing starts only after you choose files and press the action button. The media engine is not preloaded on the homepage or ordinary tool pages.

Representative tasks

What you can do with this tool

Join chapter exports

Combine clips exported with the same preset into one continuous file.

Boundaries

What to check before relying on the result

  • A missing or mismatched measured frame-rate estimate fails closed; matching estimates still cannot prove identical variable-frame-rate timing or time bases.
  • The concat path does not add transitions or normalize loudness.
Mediabunny documentationffmpeg.wasm documentationMDN WebCodecs API

How to use

  1. 1

    Choose the video files from your device.

  2. 2

    Review the detected media facts and task-specific controls.

  3. 3

    Start the local job, watch progress, or cancel to terminate the worker.

  4. 4

    Play or inspect the downloaded result before replacing the source.

Use Cases
Join chapter exports

Combine clips exported with the same preset into one continuous file.

Continue the workflow

Order compatible clips, merge, then inspect every join for timing, audio continuity, and playback.

Tips & Tricks
Start with a short representative file

Confirm codec and browser support before committing device time to a long source.

Keep the source

Every output is a new file. Retain the original until you have completed a full playback check.

FAQ

Is my media uploaded to TOOLGRID?

No. The selected files are written into an in-browser worker file system. The self-hosted encoder assets are downloaded separately, but TOOLGRID does not receive the selected media for processing.

Why can a local media job be slow?

The compatibility encoder runs single-threaded in WebAssembly and is limited by device CPU, available memory, source duration, resolution, codecs, and browser behavior.

What should I verify in the result?

Check playback, duration, seeking, video and audio synchronization, expected tracks, visual quality, and actual file size in the browser or player used by your audience.

Continue this workflow

Useful next steps

Open a nearby browser tool when you need to validate, convert, or reuse the result.

Trim VideoVideo Tools · Local→Convert VideoVideo Tools · Local→Compress VideoVideo Tools · Local→