Upload an MKV
Select a non-empty .mkv file up to 100 MB.
Free online MKV to WEBM converter
Create a VP9 WEBM version of an MKV.
Fileverses server-encodes the first readable video stream from an eligible MKV to WEBM, with Opus audio only when a first audio stream exists.
- VP9 WEBM
- Optional Opus track
- 100 MB per file
Processed by our self-hosted conversion engine
Supported files
MKV source, WEBM delivery copy.
MKVWEBM
A successful conversion creates a new VP9 WEBM from the first MKV video stream; it is not a container-only remux.
How it works
Convert MKV to WEBM deliberately
Run the queue
Fileverses submits each file sequentially to its fixed VP9/Opus FFmpeg profile.
Save the WEBM
Review a completed result where browser playback supports it and download the separately named WEBM.
What the profile does
Fixed VP9 and conditional-Opus encoding.
First video and optional first audio streams are encoded. Source metadata and chapters are removed, with no user encoder controls.
Convert MKV to WEBM100 MB MKV maximum
Only non-empty .mkv uploads at or below 100 MB are accepted, and host FFmpeg must be able to read them.
New VP9 video
The first video stream is encoded as VP9. This is not a stream copy, so size, quality, and playback results vary.
Audio is conditional
Only the optional first audio stream is encoded as Opus; video-only MKVs yield WEBM files without audio.
Source structure is removed
Metadata and chapters are removed. Alternate tracks, subtitles, attachments, trimming, resizing, bitrate, codec, and quality selection are unavailable.
MKV to WEBM FAQ
Know the output boundaries
What does MKV to WEBM encode?+−
It encodes the first video stream as VP9 and the optional first audio stream as Opus in a new WEBM file.
Can a video-only MKV convert?+−
Yes, if FFmpeg can read its first video stream. The resulting WEBM has no audio.
Does it preserve every MKV track?+−
No. It maps first video and optional first audio only; alternate tracks, subtitles, attachments, metadata, and chapters are not retained.
What are the upload requirements?+−
Use a non-empty .mkv file up to 100 MB that host FFmpeg can read.
Is this lossless or a remux?+−
No. VP9 and optional Opus are newly encoded, so neither losslessness nor source codec retention is promised.
Can I set VP9 quality or resize?+−
No. There are no controls for quality, bitrate, codec, resize, frame rate, trimming, or stream selection.
Can I convert multiple MKVs?+−
Yes. Submitted files are handled sequentially and successful results download separately.