What is ffmpeg.wasm?

ffmpegwasm/ffmpeg.wasm — explained in plain English

Analysis updated 2026-06-24

★ 17,475CAudience · developerComplexity · 3/5LicenseSetup · moderate

Mindmap

mindmap
  root((ffmpeg-wasm))
    Inputs
      Video files
      Audio files
      Stream data
    Outputs
      Transcoded media
      Recorded clips
      Browser streams
    Use Cases
      In-browser editor
      Format converter
      Client-side encoding
    Tech Stack
      WebAssembly
      JavaScript
      C
      FFmpeg

mindmap root((ffmpeg-wasm)) Inputs Video files Audio files Stream data Outputs Transcoded media Recorded clips Browser streams Use Cases In-browser editor Format converter Client-side encoding Tech Stack WebAssembly JavaScript C FFmpeg

Click or tap to explore — scroll the page freely

What do people build with it?

USE CASE 1

Build a browser-based video format converter that runs entirely client-side

USE CASE 2

Add audio trimming or transcoding to a web app without server processing

USE CASE 3

Record webcam input in the browser and convert to mp4 before upload

USE CASE 4

Create a static video editor demo for GitHub Pages with no backend

What is it built with?

WebAssemblyJavaScriptCFFmpegNode

How does it compare?

	ffmpegwasm/ffmpeg.wasm	reactos/reactos	brunodev85/winlator
Stars	17,475	17,515	17,588
Language	C	C	C
Setup difficulty	moderate	hard	hard
Complexity	3/5	5/5	4/5
Audience	developer	developer	general

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · moderate Time to first run · 30min

Requires SharedArrayBuffer, so pages need COOP and COEP headers set correctly to load the wasm core.

MIT license - free to use, modify, and ship in commercial products with attribution.

So what is it?

ffmpeg.wasm brings FFmpeg, one of the most widely used tools for converting and processing video and audio files, directly into a web browser. Normally, FFmpeg is a command-line program you install on your computer. This project ports it to WebAssembly (a format that lets compiled code from other languages run in a browser at near-native speed), which means you can record, convert, and stream video and audio entirely in the browser without sending files to a server. This opens up possibilities like in-browser video editors, format converters, or audio tools that work completely client-side. The project is written in C and JavaScript, marked as experimental, and licensed under MIT. The README does not provide further detail about supported formats, browser compatibility requirements, or usage examples beyond what is described above.

Copy-paste prompts

Prompt 1

Show me a minimal HTML page that loads ffmpeg.wasm and converts an uploaded mp4 to webm in the browser

Prompt 2

Build a React component that uses ffmpeg.wasm to extract audio as mp3 from an uploaded video file

Prompt 3

How do I configure ffmpeg.wasm in a Vite project with the right COOP and COEP headers for SharedArrayBuffer

Prompt 4

Use ffmpeg.wasm to trim a video between two timestamps and download the result

Prompt 5

Compare performance of ffmpeg.wasm vs running FFmpeg on a Node server for short clips

Frequently asked questions