Any file up to 500 MB. Drop several files and they come back as one ZIP. Many image, audio and video conversions run in your browser; anything else is uploaded and removed within the hour.
Convert your MKV video files into the efficient OPUS audio format effortlessly. This tool is ideal for users who need to extract high-quality audio tracks from video containers for playback on low-bandwidth devices.
MKV (Matroska) is a flexible multimedia container that stores video, audio, and subtitles in a single file. OPUS, conversely, is a versatile lossy audio codec designed for low-latency and high-fidelity streaming. When converting MKV to OPUS, the process involves stripping the video stream and re-encoding the remaining audio track into the OPUS container. This transformation changes the file's nature from a video-centric format to a purely audio-focused one, significantly reducing the file footprint while maintaining excellent acoustic clarity.
Both MKV and OPUS are lossy formats. Since the conversion involves re-encoding the audio track, a minor generation loss in sound fidelity may occur, though it is often imperceptible to the human ear.
We built this project so anyone can convert files without paywalls, accounts, or hidden limits. Here is what that promise means in practice.
Every converter on ConvertX is free to use: no trials, no premium tiers, and no credit packs. We will never put core conversion features behind a subscription. Whether you convert one photo or a hundred files a week, the price stays zero.
Many image, audio, and video conversions run entirely in your browser. Your files never leave your device for those jobs. When server processing is required for documents or specialized formats, uploads are handled securely and removed automatically — typically within one hour.
A quick guide to strengths and trade-offs of popular formats — so you pick the right one before converting.
Clips, streams, screen recordings, and movies.
Common extensions: MP4, WebM, MOV, MKV, AVI, MPEG
Raster and vector graphics for web, print, and photography.
Common extensions: PNG, JPG, WebP, AVIF, GIF, SVG, HEIC, TIFF
Office files, PDFs, ebooks, and plain text.
Common extensions: PDF, DOCX, XLSX, PPTX, ODT, EPUB, TXT
Music, podcasts, voice recordings, and sound effects.
Common extensions: MP3, WAV, FLAC, OGG, AAC, M4A, OPUS
