WebM Video (WEBM) packages VP8/VP9 or AV1 video with Vorbis/Opus audio in a royalty-free container designed for web streaming. Matroska Video (MKV) stores video, audio, subtitles, and chapters in an open-standard container that supports virtually every codec. This conversion changes the file's encoding, compression method, and supported feature set. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. The result is a standard MKV file readable by any compatible application. 1converter handles WEBM-to-MKV conversion server-side: files are uploaded over HTTPS, processed on isolated cloud infrastructure, and the converted output is available for download for 24 hours before automatic deletion. No account is required for standard conversions.