WEBM to FLV Converter
FileFlip converts WEBM to FLV entirely inside your browser, using FFmpeg compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert a WEBM file to FLV?#
- Drop your WEBM file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to FLV and the conversion starts on its own. FileFlip downloads 30.8 MB of WebAssembly the first time and nothing after that, then runs FFmpeg on your own machine.
- Save the FLV file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting WEBM to FLV lose quality?#
It depends on what is inside the file. WEBM is a container rather than a codec, so whether the FLV conversion copies the streams across untouched or re-encodes them is decided by the codecs that particular file happens to use.
Is it safe to convert WEBM files online?#
Yes, because nothing is uploaded. FileFlip converts WEBM files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What WEBM to FLV actually does to the file#
Converting WEBM to FLV runs on FFmpeg, downloads 30.8 MB of WebAssembly the first time and nothing after that, re-encodes or copies through depending on the codecs in the file, and drops encoded streams.
| Engine | FFmpeg |
|---|---|
| Conversion path | One step: WEBM → FLV |
| Downloaded to your browser | 30.8 MB, once, then cached by your browser |
| Quality | Decided by the codecs inside the file |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| Encoded streams | Dropped | The target format has nowhere to put it. |
What is a WEBM file?#
A WEBM file holds VP8, VP9 or AV1 video with Vorbis or Opus audio in a cut-down version of the Matroska container, restricted to codecs that carry no patent licensing so browsers can play them freely.
Choose WebM when the video is going on a web page and you want it to play in browsers without a codec licence attached to it.
Convert WebM to MP4 when the file has to leave the browser, whether that is an edit timeline, an older iPhone or a television.
What is an FLV file?#
An FLV file holds video and audio in tagged chunks meant to be streamed to Adobe's Flash Player, which is the only thing that ever played the format natively and has not shipped since the end of 2020.
There is no reason to create an FLV now; the only sensible use is holding on to one as the untouched original of something you have already converted.
Convert FLV to MP4 as soon as you find one, since the wrapper is the only thing standing between you and video that still plays perfectly well.
WEBM to FLV questions people ask#
Why did my screen recording save as a WEBM file?
Browser-based recorders and screen capture tools save WEBM because it is what the browser can encode without licensing anything. Recording in the browser goes through the MediaRecorder API, and VP8 or VP9 in WebM is the combination browsers ship by default, since encoding H.264 would mean paying for the patents. The recording is fine, it just needs converting before most editing software will take it.
What is the difference between WebM and MKV?
WebM is a deliberately narrowed version of Matroska. It uses the same container structure but only allows VP8, VP9 or AV1 video with Vorbis or Opus audio, where MKV takes any codec at all. That restriction is the point: a browser can support WebM completely, whereas supporting MKV would mean supporting every codec ever put in one.
Does converting WebM to MP4 lose quality?
Converting WebM to MP4 usually re-encodes the video and loses a little quality, because the VP9 or VP8 inside a WebM is not what MP4 players expect to find. MP4 can technically carry VP9 and AV1 now, but almost nothing in the wild plays those from an MP4, so a real conversion means encoding to H.264. Going the other way, MP4 to WebM, always re-encodes too, since H.264 is not allowed inside WebM at all.
Can WebM video have a transparent background?
WebM is one of the few video formats that carries transparency, using an alpha channel alongside VP9. That makes it the usual way to put video over a web page without a rectangular black box around it. The transparency does not survive conversion to MP4, since H.264 in MP4 has no alpha channel to put it in.