MKV (Matroska) is a flexible container used by OBS recordings, screen captures and many video tools. WebP is the modern web image format, noticeably lighter than JPG at a similar quality. This tool takes the first frame of each MKV video and saves it as a WebP, without uploading anything.
How to extract a WebP thumbnail from MKV
- Drop your MKV videos in the box above, or click to pick them. You can add as many as you like.
- WebP is already selected as the output format. Switch on other formats if you want them too.
- Optional: open Advanced Settings to resize the thumbnail by percentage, width or height, and add more sizes.
- Click Extract Thumbnails, then download each image or all of them at once. Nothing is uploaded: everything runs in your browser.
Why save MKV thumbnails as WebP?
MKV files often do not open in photo apps or simple players. Extracting the first frame as an image is a fast way to preview or catalog them without installing anything. For a poster image on a website, WebP gives you a sharp thumbnail that loads fast, and every modern browser displays it.
Frequently asked questions
Which MKV files are supported?
MKV files whose video codec your browser can decode, typically H.264, VP8, VP9 or AV1. OBS recordings in H.264 work in every modern browser.
Can I use a WebP thumbnail as a video poster?
Yes. The poster attribute of the HTML video element accepts any image the browser can display, and all modern browsers display WebP.
Are my videos uploaded?
No. The first frame is decoded and saved as an image in your browser, on your device. Your videos are never sent to a server, so this works for private files too.