FLV to MP4 Converter

Convert legacy Flash Video (.flv) files into modern, highly compatible MP4 videos. Processed entirely in your browser for ultimate speed and privacy.

Drop FLV video here or click to upload

Private Transcoding: Files stay in your browser

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About FLV to MP4

FLV (Flash Video) was once the standard for web video, but it is no longer supported by modern browsers or mobile devices. MP4 (MPEG-4 Part 14) is the current industry standard, offering excellent compression and universal compatibility. Converting your archive of FLV files to MP4 ensures they remain playable on iPhones, Android devices, and all modern web browsers.

Our tool uses Client-Side Rendering (CSR) via FFmpeg.wasm. Unlike traditional converters that require you to upload huge video files to a remote server, we bring the processing power to you. Your video data is transcoded directly in your browser's memory, ensuring your content remains 100% private.

How to Convert FLV to MP4

  1. Upload: Select your .flv file by dragging it into the zone or using the file picker.
  2. Initialize: The browser loads the WebAssembly video engine to prepare for conversion.
  3. Transcode: Click "CONVERT TO MP4". The tool will remux the video stream into an MP4 container.
  4. Save: Once finished, the high-quality MP4 file will be saved directly to your Downloads folder.

Frequently Asked Questions

Is there a file size limit?

The limit is determined by your browser's available memory. For the best experience, we recommend converting files under 500MB.

Is the video quality lost?

Our tool uses smart remuxing technology. If the source video uses compatible codecs (like H.264), we move the data into the new container without re-encoding, resulting in zero quality loss.

Are my videos private?

Yes. Because we use WebAssembly, the conversion happens locally. No video data is ever sent to our servers.

Why is it taking a moment to start?

The first time you use the tool, your browser needs to download the WebAssembly engine (approx. 25MB). Subsequent conversions will be much faster.