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FLV to MP4 Converter (Free, Online, No Upload)

Convert any FLV file to MP4 right in your browser. Nothing gets uploaded to a server. FLV is a legacy Flash video format that modern browsers no longer support. Converting to MP4 makes your video playable everywhere. The conversion runs locally using FFmpeg compiled for your browser.

Try it in your browser

Loading FFmpeg engine... (~31 MB)

Use the API

curl -X POST https://renderio.dev/api/v1/run-ffmpeg-command \
  -H "X-API-KEY: ffsk_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
  "ffmpeg_command": "-i {in_video} -c:v libx264 -crf 23 -c:a aac -movflags +faststart {out_video}",
  "input_files": {
    "in_video": "https://example.com/input.flv"
  },
  "output_files": {
    "out_video": "output.mp4"
  }
}'

Need an API key? Get your free API key to start processing files programmatically.

Common Variations

High quality archival
-i input.flv -c:v libx264 -crf 18 -preset slow -c:a aac -b:a 192k output.mp4
Downscale to 720p
-i input.flv -vf scale=-2:720 -c:v libx264 -crf 23 -c:a aac output.mp4
Fast processing
-i input.flv -c:v libx264 -preset fast -crf 25 -c:a aac output.mp4

Related Operations

Free AVI to MP4 Converter Online | RenderIOWebM to MP4 Converter Online Free, No Upload | RenderIOFree MKV to MP4 Converter Online | RenderIOCompress Video Online Free, No Upload Required | RenderIO

Need to process at scale?

Automate this with the RenderIO FFmpeg API. Process thousands of files programmatically or through no-code video automation.

Get your API key