Free online converter · No signup
Free MKV to WebM converter
Convert MKV to WebM online free — also supports MP4 and MOV. Browser-based with ffmpeg.wasm.
Choose a tool
Converters & extractors
Pick a converter or extractor. Frame tool includes Start, End, and All frames.
Images
FreeImage converter
JPG, PNG, WebP, GIF — convert privately in your browser.
Open tool →Images
FreeImage rescale
Shrink 20–30 MB photos down to 10–15 MB (your target).
Open tool →Video
FreeMP4 → WebM
MKV, MP4, or MOV to WebM. Free, no upload.
Open tool →Video
FreeMP4 → GIF
MP4, MOV, or MKV to animated GIF. Free, no upload.
Open tool →Frames
FreeExtract video frames
Start, end, or all frames as PNG at source resolution.
Open tool →YouTube
Free + AIThumbnail extractor & editor
Extract thumb, overlay text, AI face replace (Studio+).
Open tool →Social
Video downloadYouTube extractor
Download YouTube video from a public link when available.
Open tool →Social
Video downloadTikTok extractor
Download TikTok video (MP4) from a public link.
Open tool →Social
Video downloadFacebook extractor
Download Facebook / fb.watch video when publicly available.
Open tool →Social
Video downloadAll social extractors
Download video from YouTube, TikTok, Facebook, Instagram, X, Vimeo.
Open tool →MKV / MP4 to WebM converter
FreeConvert MP4, MKV, or MOV to WebM in the browser — free video converter, no upload.
Runs in your browser (ffmpeg.wasm) — first run downloads ~25 MB. Accepts MKV, MP4, MOV, M4V. In-browser attempt allowed up to ≤1024 MB / ≤1080p, but large files often OOM (especially above ~250–500 MB). Prefer uploading an existing WebM, or convert offline (HandBrake / ffmpeg) then Upload. Over 1024 MB must be offline.
Choose a video, then Download WebM. Nothing is uploaded to our servers.
convert-v7-2026-08-08
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FAQ
How to use this tool
Steps for this page, plus privacy basics.
Image conversion, rescale, frame extract, and text overlays on thumbnails are free. Social video download is free when a public file is available. AI thumbnail face replace uses Studio plan credits. No credit card for free tools.