Add your FLV file
Drop one or more .flv files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
FLV to WEBM
Converting .flv video to .webm means re-encoding the picture and sound into a different container and codec family, and this page does it entirely in your browser. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop FLV files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting Flash video to WebM video
Converting .flv video to .webm means re-encoding the picture and sound into a different container and codec family, and this page does it entirely in your browser. An .flv file is a Flash Video container, the format that powered most web video during the 2000s. YouTube, news sites, and early streaming platforms delivered .flv streams into the Flash Player plugin before HTML5 video replaced the whole stack.
A .webm file is an open, royalty-free video container built specifically for the web. It restricts itself to free codecs, VP8, VP9, or AV1 for video with Vorbis or Opus for audio, so any browser can play a .webm without patent licensing concerns. For this route the practical draw is free of patent royalties end to end and vP9 and AV1 deliver excellent compression efficiency — balanced against older iPhones and legacy Safari versions cannot play it, which is worth knowing before you commit a large batch.
Why convert FLV to WEBM?
The practical trigger for this conversion is usually a mismatch: with .flv, no mainstream player ships FLV support anymore. Switching to .webm buys you free of patent royalties end to end, which is why it is the better fit for serving HTML5 video without codec license fees. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
FLV vs WEBM at a glance
| Aspect | Flash video (.flv) | WebM video (.webm) |
|---|---|---|
| Format type | Container — quality depends on the codecs and settings inside | Container — quality depends on the codecs and settings inside |
| How it stores data | a simple sequence of tagged audio, video, and script packets designed for progressive download and RTMP streaming | structured as a deliberately restricted subset of Matroska's EBML layout |
| Strongest at | recovering clips downloaded during the Flash era | serving HTML5 video without codec license fees |
| Weak spot | no mainstream player ships FLV support anymore | older iPhones and legacy Safari versions cannot play it |
| Metadata | an onMetaData script tag embeds duration, dimensions, and encoder details; there is no standard field set for titles or authorship | only a minimal set of Matroska tags such as title and language is defined for WebM; the spec deliberately omits attachments and rich tagging |
Pick WEBM as the output
Select .webm in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if WEBM is selectable, the route is real and validated.
Convert on your device
Press Convert. The conversion runs on an FFmpeg engine compiled to WebAssembly, executing entirely inside your browser tab.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid WEBM file. Outputs keep the original filename with the .webm extension.
FLV to WEBM questions, answered
Will converting FLV to WEBM lose quality?
Both sides are re-encoded, so expect a small generation loss controlled by the quality setting: flv is container-oriented and webm is container-oriented. For visually or audibly transparent results keep quality high; for smaller files lower it and compare.
Is it private to convert FLV files here?
Yes — the .flv file is processed inside your browser tab and never uploaded. The conversion runs on an FFmpeg engine compiled to WebAssembly, executing entirely inside your browser tab. Close the tab and the file is gone from memory.
Where will the WEBM file work?
Chrome, Firefox, and Edge have played WebM for over a decade, and Safari added playback in 2021 starting with version 14.1 on macOS, with iOS following in iOS 15. Beyond browsers the picture thins out quickly, since many televisions, set-top boxes, and editors still expect MP4.
Will the WEBM file be bigger or smaller than my FLV?
It depends on the content: structured as a deliberately restricted subset of Matroska's EBML layout. Convert one representative file first and compare before batch-processing a large set.
What happens to the metadata in my FLV file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, an onMetaData script tag embeds duration, dimensions, and encoder details; there is no standard field set for titles or authorship; none of it is transmitted anywhere because the file never leaves your browser.
Can I convert WEBM back to FLV?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .flv → .webm → .flv is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.