New ffmpeg.wasm tool

Private Video Format Converter

Convert a video to MP4 or WebM locally with quality, resolution, and audio controls. The FFmpeg engine is hosted with the site and loads only when you start processing.

Free ToolFFmpeg loads only when needed

Video Format Converter

Convert a local video to MP4 or WebM in your browser with ffmpeg.wasm. No backend upload is required.

Drop video here or click to upload

MP4 and WEBM are the safest first-version inputs.

Max file size: 200MB

No video uploaded

Conversion settings

Choose output format, quality, resolution, and audio before processing.

Output format

H.264 video with AAC audio for broad compatibility.

Resolution

Keep the source dimensions.

Video qualityCRF 24

Higher qualitySmaller file

Keep audio

Disable for a smaller silent video.

Audio bitrate

Engine

ffmpeg.wasm

Output

MP4

Audio

128 kbps

Ready0%

Converted video

Review the output size, format, and local download.

Output size

No converted video yet

Format

MP4

Size change

Not ready

Upload a video, choose MP4 or WebM, and process it to preview the output here.

The video stays on your device. FFmpeg runs in the browser only after you start processing, and the large WebAssembly engine is served from this site.

Quick answer

A video format converter re-encodes a source video into a different browser-friendly output format.

This first version focuses on MP4 and WebM because they cover the most common web publishing and sharing needs.

Best inputs

Common video files

MP4, WEBM, MOV, and other common containers are the best first inputs for browser-side conversion.

Destination format choice

Choose MP4 for broad compatibility or WebM when the destination is a modern browser workflow.

Conversion method

The tool writes the source video into browser memory and uses ffmpeg.wasm to create a new MP4 or WebM file.

MP4 output uses H.264 video and AAC audio for broad compatibility.

WebM output uses VP9 video and Opus audio for browser-native publishing.

Optional quality and resolution controls help keep the result practical for upload or sharing.

Example, Assumption, and Limitation

Use the result as a practical estimate or transformation, then confirm edge cases for critical work.

Example

Upload a small WebM screen recording, choose MP4 output, keep original resolution, and export a more widely compatible file.

Assumption

The source file is under 200MB and the current browser has enough memory to run ffmpeg.wasm.

Limitation

This browser-side converter is best for short clips. Very large videos, subtitle preservation, and batch conversion are better handled by desktop tooling.

Common use cases

These pages are built for lightweight browser-side work, examples, and planning.

Compatibility

Convert WebM or MOV clips to MP4 before uploading to systems that expect MP4.

Browser workflows

Convert MP4 to WebM when a browser-native delivery format is preferred.

Preview exports

Create a smaller preview version while keeping the original source file private.

Local testing

Test MP4 and WebM behavior without sending unpublished video to a third-party service.

Frequently asked questions

Does this video converter upload my file?

No. The selected video is processed in your browser with ffmpeg.wasm. The current tool does not send the source video to a backend.

Which output formats are supported?

The first version supports MP4 with H.264/AAC and WebM with VP9/Opus, which are practical browser-side output formats.

Can it convert every video format?

No. FFmpeg can read many containers, but browser memory, codec support, and WebAssembly limits still matter. Use smaller files and common inputs for the best result.