Batch FLV to MP4 Converter
Convert FLV to MP4 online for free. 100% secure, fast, and private local file conversion directly in your browser. No software installation required.
Why convert FLV to MP4?
FLV was the workhorse of Flash-era video — the format of 2000s web players, old tutorials, and archived course downloads. Those files are still on hard drives today, but nothing plays them anymore: no current browser runs Flash, and most apps treat FLV as an unknown file. Converting FLV to MP4 is the only practical way to keep that content usable — the video and audio are preserved while the format moves into the modern playback world.
WasmConvert reads legacy FLV files in your browser and re-encodes them to H.264 video with AAC audio in an MP4 container, dealing with the dated codecs (VP6, older H.263 or H.264, or MP3 audio) that modern players no longer recognize. Everything happens locally with no upload, so old downloads and archived course material never leave your device. There are no file-size limits, meaning even several-hours-long FLV recordings can be converted in one go at a quality you choose.
Common use cases
- Reviving old Flash-era tutorials and how-to videos that no browser can play anymore
- Archiving course downloads from the 2000s so they remain watchable as the web moves on
- Converting FLV screen recordings or webcam clips into files that phones and editors accept
How to convert FLV to MP4 (Step-by-step)
Select or drop your file
Click "Choose Files" or drag and drop your FLV file directly onto this page.
Set target format
Make sure the output format is set to MP4.
Local conversion
Click convert. Your file is processed entirely in your browser memory - no data is uploaded to our servers.
Save instantly
Once finished, your MP4 file is ready to download.
FLV is a legacy Flash video format. It is highly recommended to convert FLV to MP4 for modern playback.
MP4 is the most widely supported digital multimedia container format. It is universally compatible with all web browsers, smartphones, and media players.
Pro tips for FLV to MP4 conversion
- FLV files can contain H.264 video that only needs remuxing into MP4, or legacy VP6 and H.263 video that must be fully re-encoded — the conversion time tells you which kind you have.
- Some old FLVs use Nellymoser audio, which modern players never supported; the MP4 conversion re-encodes it to AAC so the sound becomes audible everywhere.
- If a downloaded FLV will not open at all, its header may be damaged by an interrupted download — try converting it anyway, since many decoders can recover a readable stream from the rest of the file.