uDocumentViewer
Convert.flv

Convert FLV to MP4 online

100% localFiles never leave your device — no upload, no account, no tracking.
About FLV to MP4

Convert legacy FLV (Flash) videos into MP4 that plays everywhere now that Flash is gone. We re-encode to H.264 with ffmpeg.wasm at a quality you control.

The transcode runs entirely in your browser. Your FLV file never leaves your device.

How it works
  1. 01

    Add an FLV

    Drop your FLV file onto the page or pick it from your device.

  2. 02

    Set quality

    Choose a CRF value for the output quality.

  3. 03

    Convert

    Click Convert to encode an MP4 locally with ffmpeg.wasm.

  4. 04

    Download

    Save the MP4 file.

Features
H.264 outputmodernizes old videoadjustable quality
Frequently asked
How does the FLV to MP4 converter work?
Convert legacy FLV (Flash) videos into MP4 that plays everywhere now that Flash is gone. We re-encode to H.264 with ffmpeg.wasm at a quality you control.
Are my files uploaded to a server?
No. Everything runs entirely in your browser using local JavaScript and WebAssembly. Your files never leave your device.
Does it cost anything or require an account?
No. The converter is free, needs no sign-up, and runs locally in your browser.
Related converters
Open these files in a viewer